S. No. No.: Physical Chemistry [PDF]

Zitiervorschau

HANDBOOK OF CHEMISTRY

S. No.

CONTENTS

Page No.

PHYSICAL CHEMISTRY 1. 2.

Some Basic Concepts of Chemistry Solutions

2-3 6-7

3.

Redox Reactions

10

4.

Electrochemistry

12-15

5. 6.

Behaviour of gases Atomic Structure

18-19 20-22

7.

Chemical Kinetics

24-25

8.

Thermodynamics & Energetics

28-31

9. 10.

Chemical Equilibrium Ionic Equilibrium

32-34 36-40

11.

Solid State

42-43

12.

Surface Chemistry

46-47

1.

INORGANIC CHEMISTRY Some Important Increasing order

50-52

2.

Periodic Table

53-57

3.

Chemical Bonding

60-69

4. 5.

s-Block elements p-Block elements

72-74 77-88

6.

Coordination Chemistry

90-93

7.

d-Block (Transition Elements)

94-97

8. 9.

Metallurgy Hydrogen

99-100 102-103 ORGANIC CHEMISTRY

E

1.

Table for IUPAC Nomenclature

2. 3.

Isomerism Reaction Mechanism

4.

Practical Organic Chemistry

5.

Distinction b/w pair of compound

116-119

6. 7.

Hydrocarbons Haloalkanes & Grignard Reagents

122-125 128-130

8.

Alcohol, Ether and Phenol

132-138

9.

Carboxylic Acid

10. 11.

Amines Organic Reagents

142-144 146-149

12.

Organic Name Reactions

150-152

13.

Polymers

14.

Carbohydrates

106 108-110 112 114

140

154 156-157

PHYSICAL CHEMISTRY

Chemistry HandBook

C HAP TE R

ALLEN

SOME BASIC CONCEPTS OF CHEMISTRY SOME USEFUL CONVERSION FACTORS 1 Å = 10–10 m, 1 nm =10–9 m 1 pm = 10–12 m 1 litre = 10–3 m3 = 1 dm3 1 atm = 760 mm or torr=101325 Pa or Nm–2

1 bar = 105 Nm–2 = 105 Pa 1 calorie = 4.184 J 1 electron volt (eV) = 1.6022 × 10–19 J (1 J = 10 ergs) 7

(1 cal > 1 J > 1 erg > 1 eV)

RELATIVE ATOMIC MASS OR RELATIVE MOLECULAR MASS Mass of one atom or molecule w.r.t. 1/12th of 12C atom C® 12 H2O ® 18 It is unitless

ATOMIC MASS OR MOLECULAR MASS Mass of one atom or molecule in a.m.u. C ® 12 amu H2O ® 18 amu

GRAMS ATOMIC MASS OR GRAM MOLECULAR MASS

ACTUAL MASS mass of one atom or molecule in grams C ® 12 × 1.66 × 10–24 g H2O ® 18 × 1.66 × 10–24 g

Mass of one mole of atom or molecule C® 12 g H2O ® 18 g It is also called molar weight

DEFINITION OF ONE MOLE One mole is a collection of that many entities as there are number of atoms exactly in 12 g of C-12 isotope.

1g 1u = 1 amu = (1/12)th of mass of 1 atom of C12 = N = 1.66 × 10-24 g A

For elements • 1 g atom = 1 mole of atoms = NA atoms • g atomic mass (GAM) = mass of NA atoms in g. • Mole of atoms =

Mass ( g ) GAM or molar mass

• 1 g molecule = 1 mole of molecule = NA molecule • g molecular mass (GMM) = mass of N A molecule in g. • Mole of molecule =

Mass ( g ) GMM or molar mass

1 mole of substance 23

Contains 6.022 × 10 particles Weight as much as molecular weight / atomic ionic / weight in grams If it is a gas, one mole occupies a volume of 22.4 L at 1 atm & 273 K

2

For ionic compounds

• 1 g formula unit = 1 mole of formula unit = NA formula unit. • g formula mass (GFM) = mass of N A formula unit in g. • Mole of formula unit =

Mass ( g ) GFM or molar mass

Average or mean molar mass The average molar mass of the different substance present in the container Mavg =

M1n1 + M2n2 + .... n1 + n2 + ....

Here M1, M2 are molar mass of substances and n1, n2 are mole of substances present in the container.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

For molecule

E

Chemistry HandBook

CHAP TER

ALLEN

DENSITIES Mass Density = , unit : g/cc volume Relative Density =

VAPOUR DENSITY Ratio of density of vapour to the density of hydrogen at similar pressure and temperature.

Density of any substance Density of reference substance

* mass % of an element in a compound =

Vapour density =

Molar mass 2

atomicity of an element × atomic mass of an element ´ 100 molecular mass of compound

Molarity (M)

V(L)

V(L) mass in (g) W(g)

¸ molar mass × molar mass

¸ 22.4 L mol—1

Number of Moles (n)

NA

× 22.4 L mol

—1

Volume of gas (in L) at NTP/STP

NA

Number of Particles r STOICHIOMETRY BASED CONCEPT

r EQUIVALENT WEIGHT

[Concept of limiting reagent] aA + bB ®cC + dD • a,b,c,d, represents the ratios of moles, volumes [for gaseous] and molecules in which the reactants react or products formed. • a,b,c,d, does not represent the ratio of masses. r HOW TO FIND L.R.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

• Case I : If data of only one reactant is given then treat that reactant as L.R. and other reactants as excess reagent.

E

• Case-II : If data of more than one reactants are given then first convert all the data into moles then divide the moles of reactants with their respective stoichiometric coefficient. The reactant having minimum ratio will be L.R. then find the moles of product formed or excess reagent left by comparing it with L.R. through stoichiometric concept.

• Equivalent weight =

molar weight valency factor ( VF )

• V.F. for elements = Valency Ex.:

Na =1, Al=3, N2=6, O2 =4, H2=2

• V.F. for ionic compounds (salts) = total charge on cation / anion Ex. : Na2+1 CO3–2 ® V.F. = +1×2 = 2 K4+1[Fe(CN)6] = V.F. = +1× 4 = 4 • V.F. for acids = No. of replaceable H+ ions HCl =1, H2SO4= 2, H3PO4= 3 H3PO3=2, H3PO2 =1 • V.F. for bases = No. of replaceable OH– • NaOH =1, Ba(OH)2=2, Ca(OH)2=2, Al(OH)3=3

KEY POINTS

r r

Dulong & Petit’s law (only for solids (except Be, B, Si, C) Atomic mass × specific heat (in Cal/grams °C) » 6.4 Victor -Mayer’s method is used to determine molecular weight of volatile compound.

3

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Chemistry HandBook

4 ALLEN

IMPORTANT NOTES

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

5

Chemistry HandBook

C HAP TE R

ALLEN

SOLUTIONS =

Normality (N) No. of Gram Equivalents of solute Volume of solution (L)

=

Formality (F) Mass of solute (g)

=

Molarity (M) No. of moles of solute = Volume of solution (L)

Relation b/w M&N N=M× Valency factor

=

% by Mass (w/W) Mass of solute (g) × 100 Mass of solution (g)

Relation b/w m & X XB m×(M.wt)A = XA 1000

Strength of solution (S) Mass of solute (g) = Volume of solution(L)

PPM (by mass) Mass of solute(g) × 106 Mass of solution(g)

=

PPM (by volume) Volume of solute × 106 Volume of solution

PPM (by w/V) Mass of solute (g) = × 106 Volume of solution (mL)

COLLIGATIVE PROPERTY

Solid-Liquid System

Liquid: Volatile solvent (A) & volatile solute (B) P' A=XAPAo & P' B =XBPBo Ptotal = P'A+P'B=PoA XA + PoBXB o Ptotal = (P B -PoA)XB + PoA P'A=YAPT & PB'=YBPT

Solid : Non-volatile solute(B) & Liquid : volatile solvent (A) n A o o Ptotal=PA XA =n +n ×PA (QPBo=0) A B

(Dalton law for gaseous mixtures)

P'A=PAoXA = YAPT o P'B=P BXB=YBPT (YA & YB : mole fraction in vapour phase)

Raoult's law

PAo-PS =XB PAo Lowering of vapour pressure = DP = PAo-PS (RLVP)=

Derived from RLVP : o PA -PS nB nA PS

Depression in Freezing Point(DT f)

DTb=(Tb)solution - Tb = i×m×Kb Kb = molal elevation constant or ebullioscopic constant for a solvent

DTf=(T f)-(T f)solution = i×m×K f K f = molal depression constant or Cryosopic constant for a solvent

A -P S 0 PA

DPµ

i× nB nA

nB nA

Kf =

RTo2b ×M.wt) 1000 × DHvapour

Kb=

RTo2 b 1000 × Lvapour

ent solv tion solu

Po PS

DTb o

Osmotic Presure (p)

K f=

RTo2f ×M.wt) 1000 × DHfusion

RTo2 f 1000 × Lfusion

Kf=

Liquid solvent

Tb Tb Temperature/K

6

o

Osmosis : Net flow of solvent molecules from dilute solution to concentrated solution through semi-permeable membrane. p = hdg For dilute solution : p = i × CRT

* Isotonic solution : p1 = p2 (Primary condition) At constant T; C1 = C2 (secondary condition)

Vapour pressure

0

Vapour pressure

P

Observed colligative property Calculated colligative property Calculated Molar Mass Observed Molar Mass For i=1 : Neither Association nor Dissociation Eg. : Sugar, Glucose, Urea etc. Dissociation (i>1) i =1 + (n-1)a n=total no. of ions a=Degree of dissociation Association (i>1) i =1 - a+a/n n=No. of solute particles asso. a = Degree of Association

Elevation in Boiling Point (DTb) o

For dilute solution (nB (VP) calculated (BP)observe d < (BP) calculated (A–A) & (B–B)>(A–B) Vapour pressur e of solution

o

P2

x 1=0 x2=1

P P

P1

o 1

P2

x1=1 x1=1® x 2=0 ¬x1=1

mole fraction

DHmix > 0 DSmix > 0

NON-IDEAL SOLUTION NEGATIVE DERIVAT ION Do not Obey Raoult's Law (VP)obser ved < (VP) calcul ated (BP)observed > (BP) calculated (A-A)&(A–B) 0 DG < 0

of solution

O 2

Vapour pressure

IDEAL SOLUTION Obey Raoult's Law (VP)observed = (VP) calculated (BP)observed = (BP) calculated (A–A)=(A–B)=(B–B)

Vapour pressure

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Konowaloff's Rule : The vapour phase is richer in more volatile component than the less volatile component.

x1=0 x2=1

P P2

O 1

P1

mole fraction

DHmix0

x =1 x1=1® x 1 2=0 ¬x1=1

DVmix< 0 DG PR V

t

At high pressure, Vanderwaal's eqn is PVm - Pb = RT

t

At low pres. or Moderate pressure Vanderwaal's eqn is PVm +

a­ force of attraction­ liquification­; b­, effective size of molecule ­, incompressible vol ­,

t

t

a = RT Vm

At very low pressure, high temp. a real gas behaves like an ideal gas. Gases having ­value of a; will have ­TC; ­rate of liquefaction.

compressible vol ¯ Compressibility factor (z) =

( Vm ) obs = P ( Vm ) obs Vi

RT

If z = 1, the gas show ideal gas behaviour. If z > 1, the gas show positive deviation. If z < 1, the gas show negative deviation.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

IMPORTANT NOTES

E

19

Chemistry HandBook

CHAPTER

ALLEN

ATOMIC STRUCTURE IMPORTANT DEFINITIONS Proton (mP) /anode rays

Neutron (mn)

Electron(me) / cathode rays

mass =1.67 × 10–27 kg

mass = 1.67 × 10–27 kg

mass = 9.1 × 10–31 kg

mass = 1.67 × 10–24 g

mass = 1.67 × 10–24 g

mass = 9.1 × 10–28 g

mass = 1.00750 amu

mass = 1.00850 amu

mass = 0.000549 amu

e/m value is dependent on the nature of gas taken in discharge tube.

e/m of electron is found to be independent of nature of gas & electrode used.

ATOMIC MODELS

REPRESENTATION OF AN ELEMENTS 5

Atom ic num ber

A Z

X

S ym bol of the elem ent

5 5

Terms associated with elements : 5

Atomic Number (Z) : = No. of protons Electron = Z – C (charge on atom)

5

5

5

The volume of the nucleus is very small and is only a minute fraction of the total volume of the atom. Nucleus has a diameter of the order of 10 –13 cm and the atom has a diameter of the order of 10–8 cm.

5

Thus, diameter of the atom is 105 times to the diameter of the nucleus and volume of atom is 1015 times to volume of nucleus.

Mass number (A) =Total number of neutron and proton present A = Number of proton + Number of Neutrons Isotopes : Same atomic number but different mass number Ex. : 6C12, 6C13, 6C14

5

Isobars : Same mass number but different atomic number

ELECTROMAGNETIC SPECTRUM 5

RW ®MW ®IR ®Visible ®UV ®X-rays ®CR

Isodiaphers : Same difference in the number of neutrons & protons

5 5

(Radiowaves ®Microwaves ®Infrared rays ®Visible rays ®Ultraviolet rays ®X-rays ®Cosmic rays) Wavelength decreases ¾¾¾¾¾¾¾¾¾¾¾® Frequency and energy increases ¾¾¾¾¾¾¾®

Ex. 5B11, 6C13

5

• c=nl

Ex. 1H3, 2He3 5

5

Isotones : Having same number of neutrons Ex. 1H3, 2He4

5

Isosters: They are the molecules which have the same number of atoms & electrons Ex. CO2, N2O

5

Isoelectronic:Species having same no. of electrons Ex. Cl–, Ar, S2–

20

Thomson : An atom considered to be positively charged sphere where e– is embedded inside it. Drawback : Cannot explain stability of an atom. Rutherford Model of an atoms : Electron is revolving around the nucleus in circular path. RN = R0(A)1/3, R0 = 1.33 × 10–13 cm [A mass number, RN = Radius of nucleus] SIZE OF NUCLEUS

•T =

1 n

• l= •E =

c n

•n =

1 n = l c

hc = hn , h = 6.626 × 10–34 Js l

12400 eV •E = l (Å)

•Total amount of energy transmitted E = nhn = n = number of photons

nhc l

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

M ass num ber

E

Chemistry HandBook

CH APTER

ALLEN

HYDROGEN SPECTRUM

BOHR’S ATOMIC MODEL Theory based on quantum theory of radiation and the classical laws of physics

K ( Ze) ( e) mv2 = • r r2 nh • mvr = or mvr = nh 2p • Electron remains in stationary orbit where it does not radiate its energy. • Radius : r = 0.529 ´

n2 Å Z

• Velocity : v = 2.188 ´ 106

Z -1 ms n

• Rydberg’s Equation :

1ù 1 é1 = n = RH ê 2 - 2 ú ´ Z2 l ë n1 n2 û

R H @ 109700 cm-1 = Rydberg constant

• For first line of a series n2 = n1 +1 • Limiting spectral line (series limit) means n2 = ¥ • Ha line means n2 =n+1; also known as line of longest l, shortest n, least energy • Similarly Hb line means n2 = n1 +2 • When electrons de-excite from higher energy level (n) to ground state in atomic sample, then number of n ( n - 1) 2 • When electrons de-excite from higher energy level (n2) to lower energy level (n1) in atomic sample, then number of spectral line observed in the spectrum

Z2 •Total energy (KE + PE) = –13.6 × 2 eV/atom n

spectral lines observed in the spectrum =

KZe2 - KZe2 KZe2 , PE = , KE = 2r r 2r PE = –2KE, KE = –TE, PE = 2TE v • Revolutions per sec = 2pr

• TE = -

=

( n2 - n1 )( n2 - n1 + 1)

2 • No. of spectral lines in a particular series = n2 – n1

2pr v • Energy difference between n1 and n2 energy level

• Time for one revolution =

Hydrogen

1 ö eV 1 ö æ 1 æ 1 DE = E n2 - E n1 = 13.6 ´ Z2 ç 2 - 2 ÷ = IE ´ ç 2 - 2 ÷ è n1 n2 ø atom è n1 n2 ø

where IE = ionization energy of single electron species. • Ionization energy = E¥ - EG.S. = 0 - EG.S. EG.S.= Energy of electron in ground state

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

n=1

E

Spectrum

Lyman ® Any higher orbit ® 1 [Found in U.V. region]

Pfund

® Any higher orbit ® 5 [Found in I.R. region]

4

5

3

L

M

N

O

E1

< E2

< E3

< E4

E3–E2 >

E4–E3 >

E5–E4 >

10.2

1.89

0.66

0.31 eV

Å

(n1)

Balmer ® Any higher orbit ® 2 [Found in Visible region] Paschen ® Any higher orbit ® 3 [Found in I.R. region] Brackett ® Any higher orbit ® 4 [Found in I.R. region]

2

K

(n2)

–0.85 –0.54 eV

12.1 12.75 13.06

KEÅ PEQ TEQ st Ground I E.S 2ndE.S State (Excited State)

3rdE.S

At n = ¥ is 0 At n = ¥ is 0 At n = ¥ is 0

4thE.S

21

Chemistry HandBook

CHAPTER

de-BROGLIE HYPOTHESIS • • •

• •

ALLEN

HEISENBERG UNCERTAINITY PRINCIPLE

All material particles posses wave character as well as particle character. h h l= = mn p The circumference of the nth orbit is equal to n times of wavelength of electron i.e., 2prn = nl Number of waves = n = principal quantum number 150 Å Wavelength of electron ( l ) @ V ( volts ) h l= 2mKE

•

•

•

According to this principle, “ it is impossible to measure simultaneously the position and momentum of a microscopic particle with absolute accuracy” If one of them is measured with greater accuracy, the other becomes less accurate. h h or ( Dx ) ( Dv ) ³ 4p 4pm where Dx =Uncertainity in position Dp = Uncertainity in momentum Dv = Uncertainity in velocity m = mass of microscopic particle Heisenberg replaced the concept of orbit by that of orbital. Dx.Dp ³

QUANTUM NUMBER

In an atom each shell, subshell, orbital and electron are designated by a set of 4 quantum numbers. Principal quantum number (By Bohr) Þ Indicates = Size and energy of the shell, distance of e– from nucleus Þ Values n = 1, 2, 3, 4, 5..................... h Þ Angular momentum = n ´ 2p Þ Total number of e–s in a shell = 2n2 Þ Total number of orbitals in a shell = n2 Þ Total number of subshell in a shell = n

5

Azimuthal/Secondary/Subsidiary/Angular momentum quantum number (l) Þ Given by = Sommerfeld Þ Indicates = Sub shells Þ Values Þ 0, 1..............(n–1) Þ Indicates shape of Sub shell Value Values of l Initial from of n [Shape] word eg. l = 0 (s) [Spherical] Sharp If n = 4 l=1 [p] [Dumb bell] Principal l=2 [d] [Double dumb bell] Diffused l=3 [f] [Complex] Fundamental Þ Total no. of e–s in a sub shell = 2(2l + 1) Þ Total no. of orbitals in a sub shell = (2l + 1) Þ Orbital angular momentum h = h l ( l + 1) = l ( l + 1) 2p h = Planck's constant

5 RULES FOR 5 FILLING OF 5 ORBITALS 5

22

Þ

For H & H- like species all the subshells of a shell have same energy. i.e. 2s = 2p 3s = 3p = 3d 5 Magnetic quantum number (m) Þ Given by Linde Þ Indicates orientation of orbitals i.e. direction of electron density. Þ Value of m = –l .........0.........+l Þ Maximum no of e's in an orbital = 2 (with opposite spin) py pz m for p sub shell = p x –1 0 +1 m for d sub shell = dx y –2

5

dyz –1

d z2 0

dxz +1

d x 2– y 2 +2

Spin quantum number (ms or s) Given by Uhlenback & Goudsmit Values of s = ±½ Total value of spin in an atom = ±½ ×number of unpaired electrons Spin angular momentum =

s ( s + 1)

h 2p

Aufbau principle : The electrons are filled up in increasing order of the energy in subshells. 1s22s 22p 63s23p64s23d104p65s24d105p66s24f145d106p67s25f146d10 (n + l) rule : The subshell with lowest (n + l) value is filled up first, but when two or more subshells have same (n + l) value then the subshell with lowest value of n is filled up first. Pauli exclusion principle : Pauli stated that no two electrons in an atom can have same values of all four quantum numbers. Hund's rule of maximum multiplicity : Electrons are distributed among the orbitals of subshell in such a way as to give maximum number of unpaired electrons with parallel spin.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

5

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

23

Chemistry HandBook

CHAP TER

ALLEN

CHEMICAL KINETICS —

x = order of reaction w.r.t. A y = order of reaction w.r.t. B x+y = n (overall order of reactions) Order is an experimental quantity It may be 'o', +ve, -ve or fractional Unit of K = [mol L-1]1-n× time—1 = (atm)1-n × time—1 K depends upon temperature, catalyst & nature of reactant.

COMPLEX R EACTIONS These type of reactions complete in multi step : Eg. : 2N2O5 ®4NO2 + O2 (Fast)

(ii) NO 2 + NO3 ® NO 2 + NO + O2 (Slow) (iii) NO + NO3 ® 2NO 2

—

OI +Cl

! Mo l e cu l a ri t y i s t h e

!

!

total number of reacting species participating in an elementary reaction. It is a theoret ical quantity & have only "integer values (i.e. 1,2,3). Molecularity >3 is very rare.

Pseudo First Order Reaction

These type of reactions complete in single step. If n1A+n2B ®Product n1 n2 Rate law = k[A] [B] Order = n1 + n2 For elementary reaction fractional order is not possible. In elementary reaction molecularity is equal to its order. Zero order reactions can never be an elementary reaction.

where, K = Rate constant or specific reaction rate.

(i) 2N2O5 ƒ 2NO2 + 2NO3

—

ELEMENTARY R EACTIONS

Rate Law (Experimental Expression) x y Rate = K[A] [B]

l

OH—

the experimental observations are given below Exp. [OCl—] [I—] [OH—] d[IO —]/dt 1 0.0017 0.0017 1.0 1.75 2. 0.0034 0.0017 1.0 3.50 3. 0.0017 0.0034 1.0 3.50 4. 0.0017 0.0017 0.5 3.50 From experimental observations : Rate law = k[OCl—][I—]/[OH—] Order =1

*Rate of Disappearance of A=-d[A]/dt *Rate of Disappearance of B=-d[B]/dt *Rate of Appearance of C = +d[C]/dt *Rate of Appearance of D = +d[D]/dt —1 —1 *Unit of ROR = mol L time *ROR is always positive.

l

—

For the reaction OCl +I

Instantaneous or Average Rate of Reaction

l

Molecularity

EXPERIMENTAL OBSERVATIONS

n1A + n2B ® n 3C + n4D

Reactions having order =1 and molecularity > 1 Eg. : wHydrolysis of Ester in acidic medium. w Inversion of cane sugar.

Reactant taken in excess can't affect order of reaction

ZERO ORDER R EACTIONS E.g. : 1. Decomposition of Gases on metal surface. 2. Photochemical Reactions. 3. Enzyme catalysed reactions. Differential Rate Equation :

(Fast)

r=-d[A]/dt = k[A]0

Here rate law is written in terms of slowest step

Integrated Rate Equation

(R.D.S.) which must be free from intermediates.

[A]t = [A]0 — kt

; x=kt

Rate law = K[N2O5], Order =1 Molecularity of each reaction step is defined separately. Total molecularity of complex reaction is not defined. If not defined is not in the option then molecularity of the slowest step is equal to order of reaction. (Then in this case molecularity will be 1)

24

t1/2 = t50%=

[A]0 [A]0 ; t100% = =2t1/2 2k k

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

R ATE OF REACTION

E

Chemistry HandBook

CHAP TER

ALLEN

FIRST O RDER REACTION

th

n ORDER R EACTION

Eg. 1. All Radioactive decay 2. Pseudo First order reaction.

kt=

Integrated Rate Equation [A]0 kt = 2.303 log [A]t

Differential Rate Equation 1 r=-d[A]/dt = k[A]

n-1

1 2 1 ; n¹1 kt1/2= (n-1) [A]0n-1 1 n-1 [A]0 l It is half life method to determine order of reaction. l Hydrolysis of ester in alkali medium is second order reaction. t1/2µ

t½=t50%=0.693 k t¾=t75%=2t½

TEMPERATURE

COLLISION T HEORY

f Reacting molecules must possess a minimum amount of energy known as Threshold Energy (TE) f (ii) Proper orientation of collision. (i)

Radiation

Progress of reaction Endothermic (DH = +ve)

Concentration

DH

(E a )b (T.E.)

Activated complex

(E a)f P.E.

DH

(T.E.)

(E a)f

(Ea) b

P.E.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

E

Energy

Activated complex

kT+10 = 2 to 3 kT r2 k2 DT/10 r1 = k1 =m

m=

Nature of Reactant

TE = Potential energy of reactant + Activation Energy (Ea) Energy

1 1 1 ; n¹1 (n-1) [A]tn-1 [A]0n-1

Pressure

(b) k=Ae

—Ea/RT

n

(Arrhenius Eq )

A = Arrhenius constant / Frequency factor / pre-exponential factor Ea = Activation Energy R = Gas Constant T = Temperature (K) e—Ea/RT = Boltzmann factor —Ea/RT k/A = e = Fraction of molecules having energy ³ Ea

Progress of reaction Exothermic (DH = -ve)

DH = (Ea)f-(Ea)b = HP - HR Factors Affecting Activation Energy (a) Nature of Reactant (b) Catalyst Positive CatalystÞ ¯T.E. Þ ¯Ea Þ­Rate Negative CatalystÞ ­T.E.Þ ­Ea Þ¯Rate

Catalyst

log10 k= log10A—

Ea 2.303RT

Temperature

25

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Chemistry HandBook

26 ALLEN

IMPORTANT NOTES

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

27

Chemistry HandBook

CHAP TER

ALLEN

THERMODYNAMICS DEFINITION

INTERNAL ENERGY (U) or (E)

Deals with interaction of one body with

Sum of all molecular level energies. It is state function, depends on temperature and extensive property.

another in terms of energy. System : Part of universe under investigation

For Ideal gas : DU = nCV DT

Surrounding : Rest part of universe except system. For chemical reaction :

Boundary : Devide system & surrounding

DrE = SEprod – SEreact ¹ 0 at given T.

SYSTEM Open

Closed

isolated

Energy and matter

Only energy

Neither energy

can exchange

can exchange

nor matter

HEAT (q) Energy exchange due to temperature difference :

State function

Path function

Properties which depends only

Depends on

on initial & final state of system

path or process.

& not on process or path.

as well as intial

s = specific heat capacity

and final state

m = Amount of substance

q = msDT

C = heat capacity Cm = molar heat capacity

of the system. e.g. U, H etc.

q = nCmDT,

q = CDT,

e.g. work, heat WORK (W)

THERMODYNAMIC PROPERTIES Intensive Properties which are independent of matter (size & mass) present in system. e.g. Pressure, temperature, Melting point, density etc.

Isothermal Isochoric Isobaric Adiabatic V = const. P = const.

V2

ò

Wrev = - Pext × dV

Wirr = – Pext(V2–V1)

V1

SIGN CONVENTION

PROCESSES T = const.

Irreversible

No heat

Cyclic Initial &

exchange final state q =0

w

(+)ve

q

of system are same

Reversible process

Irreversible process

•

Slow process

• Fast process

•

At any time system

• No equilibrium between

and surrounding are

system and surrounding

in equilibrium. •

28

Psys = Psurr ±dP

• Psys = Psurr ±DP

system w

(- )ve

q

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Extensive Properties which are dependent of matter (size & mass) present in system e.g. Mass, volume, heat capacity etc.

Reversible

E

Chemistry HandBook

CHAP TER

ALLEN

FIRST LAW OF THERMODYNAMICS (FLOT)

SECOND LAW OF THERMODYNAMICS (SLOT)

Law of conservation of energy

In an irreversible process (spontaneous process) entropy of universe increases. DSsystem + DSsurr = DSuniv DSuniverse

DU = q + W

WORK DONE IN VARIOUS PROCESS Isochoric

Isobaric

Free expansion

W =0

W= –Pex(V2–V1)

Pext =0

DU=qV=nCVDT qP=nCVDT

Zero Reversible

(+) ve (-)ve spontaneous Non-spontaneous

ENTROPY(S) State function, extensive property measurement of randomness a disorderness. Sgas > Sliq > Ssolid

W=0, DU=0,q=0

Isothermal dT =0; DU=0 (for Inert gas); q =–W

S­ as temperature ­; DS = Reversible Isothermal

Irreversible Isothermal

æV ö Wrev =-nRTln ç 2 ÷ è V1 ø

é nRT nRT ù Wirr = -Pext ê P1 úû ë P2

æT ö æV ö DS = nC V ln ç 2 ÷ + nRln ç 2 ÷ è T1 ø è V1 ø æT ö æP ö DS = nCP ln ç 2 ÷ + nRln ç 1 ÷ è T1 ø è P2 ø Reversible phase transformation :

æP ö = - nRTln ç 1 ÷ è P2 ø

DS fusion =

Adiabatic : Þ

q=0

C g= P CV

DU =W= nCVDT Þ W =

CP = molar heat capacity at constant P.

CP–CV=R Þ

CV = molar heat capacity at constant V.

Dr S =

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

PVg = constant (Ideal gas)

E

TVg–1 = constant (Ideal gas)

Dr G =

Enthalpy (H) pressure, depend on temperature.

For reaction : DH = DU + DngRT

åD G f

0

( prod ) - å D f Go ( react)

DG=DGo + RTlnQ (Rev. Rxn) At equilibrium DG =0, Q = K DGo = –RTlnK

State function, extensive property, constant

DH = nCPDT = qP (Ideal gas)

å S ( product) - å S(Reactant)

Gibbs free energy (G) & spontaneity G : State function; extensive property G= H –TS DG = DH – TDS (at constant T & P) DG < 0 : Spontaneous process DG = 0 : At equilibrium DG > 0 : Non-spontaneous DG: Measurement of Non-pV work (useful work)

For Reversible adiabatic :

H = U + PV

DHvap DH fusion DS vap = ; TMP TBP

For chemical reaction :

P2 V2 - P1V1 g -1

Þ

q rev T

D rH — — — + + +

DrS + — — + + —

DrG — — + + — +

Description Reaction spontaneous at all temperatures (at low T) Reaction spontaneous at low temp. (at high T) Reaction non-spontaneous at high temp. (at low T) Reaction non-spontaneous at low temp. (at high T) Reaction spontaneous at high temp. (at all T) Reaction non-spontaneous at all temp.

29

Chemistry HandBook

CHAP TER

ALLEN

THERMOCHEMISTRY (ENERGETICS)

ENTHALPY OF FORMATION (D fH) (May be endothermic or exothermic) Change in enthalpy when one mole of a substance is formed from its constituent elements present in standard state. * For elements DfHo = 0 (for standard state) DfHo [O2(g)] =0, DfHo = S8(rhombic) = 0 o DfH [P4 (white)]=0, DfH0 = C(graphite) = 0 D r Ho =

åD H f

o

( prod.) - å D f Ho ( react.)

ENTHALPY OF COMBUSTION (DCH) (always exothermic) Change in enthalpy when 1 mole of a substance is completely burnt in oxygen. 7 C2H6 ( g) + O2 ( g ) ® 2CO2 ( g ) + 3H2O( l ) ; D CHëéC2 H6 ( g)ûù 2

å

D r Ho =

D C Ho ( react.) -

Calorific value =

å

D C Ho ( prod.)

DHcomb molecular wt

ENTHALPY OF TRANSITION Enthalpy change when one mole of one allotropic form changes to another. C( graphite ) ® C( diamond) D tran Ho = 1.9 kJ mol -1

H2O(l) ®H2O(g); DvapHo (H2O(l)) H2O(S) ®H2O(l); DfusHo (H2O(s)) H2O(S) ®H2O(g); DsubHo (H2O(s)) LAWS OF THERMOCHEMISTRY A ® B D r H = x kJ mol -1 ïü ý Lavoisier & Laplace law (i) B ® A D r H = - x kJ mol -1 ïþ

(ii) Hess Law of Constant Heat summation C

DH1 A DH3

30

DH2

DH D

B E

DH4

DH5

DH=D H1 +D H2 or DH=D H3+D H4+D H5 or DH=D H1+D H2=D H3+D H4+D H5

BOND ENTHALPY (Always endothermic) Average amount of enthalpy required to dissociate one mole gaseous bond into separate gaseous atoms. æ Sum of bond enthalpy ö æ Sum of bond enthalpy ö Dr H = ç ÷-ç ÷ è of gaseous reactant ø è of gaseous product ø

RESONANCE ENERGY DHoresonance = D f H o (experimental) - D f Ho (calculated) = D C Ho (calculated) - D C Ho (experimental)

ENTHALPY OF NEUTRALIZATION (DHneut) (Always exothermic) Change in enthalpy when one gram equivalent of an acid is completely neutralized by one g-equivalent of a base in dilute solution. SA + SB ® salt + water ; DHoneut H+(aq) + OH–(aq) ® H2O(l) ; DH =– 13.7 kCal eq–1 = 57.3 kJ eq–1 o In case of weak acid / base or both DHN < 13.7

Kcal eq

and the difference is enthalpy of ionisation of ionisation of weak species except in case of HF when DHN > 13.7 due to hydration of F–. ENTHALPY OF ATOMISATION (DHatom) (always endothermic) Change in enthalpy when one mole of molecules converts into gaseous atoms. ENTHALPY OF SOLUTION (DHsol) (may be endo or exothermic) Change in enthalpy when 1 mol of a substance is dissolved in excess of water so that further dilution does not involve any heat change. aq

CuSO4( s) ¾¾® CuSO4( aq) ; DHo( sol.) ENTHALPY OF HYDRATION (DHhydra) (always exothermic) Enthalpy change when 1 mole of anhydrous salt combine with requisite amount of water to form hydrated salt. o CuSO4( s) + 5H2 O( l) ® CuSO 4 .5H2 O( s) ; DH hyd (anhy. salt)

(hydra.salt)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

ENTHALPY OF REACTION (DHR) Amount of heat evolved or absorbed during a reaction at constant pressure.

E

Chemistry HandBook

CHAP TER

ALLEN

ENTHALPY OF HYDROGENATION (DHhydro) (Always exothermic) Enthalpy change during the complete hydrogenation of one mole unsaturated organic compound into its saturated compound. unsaturated organic compound

( = or º bond )

D

¾¾®

saturated organic compound

( - bond)

C2H2 + 2H2 ®C2H6; DHhydro

NOTE : If in a reaction heat of reactant & products are given then heat of that reaction can be measured as follows:  (a) For heat of combustion & for bond enthalpy

å ( DH ) D H = å ( B.E.)

Dr H =

C reactant

r

reactant

å ( DH ) - å ( B.E.)

-

C product product

(b) For heat of formation Dr H =

å ( DH )

f product

-

å ( DH )

f reactant

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

IMPORTANT NOTES

E

31

Chemistry HandBook

CHAP TER

ALLEN

CHEMICAL EQUILIBRIUM 5

Equilibrium represents the state of a process in which the measurable properties like :- temperature, pressure, color, concentration of the system do not show any change with the passage of time.

5

Equilibrium is a dynamic process, chemical equilibrium can be approached from both sides of reaction.

5

The state of equilibrium is not affected by the presence of catalyst. It only helps to attain the equilibrium state in less or more time.

5

Equilibrium can be attained both in homogeneous & heterogenous system.

GRAPHS

Consider a reversible reaction, rf ˆˆˆ † aA + bB ‡ˆˆ ˆ cC + dD

Rate of forward reaction (rf) = rate of backward reaction (rb) So, at equilibrium,

Reactants

[ XC ]c [ XD ]d [ XA ]a [ XB ]b

In terms of mole fraction

rb

The active mass of solid & pure liquid is a constant quantity (unity) because it is an intensive property.

B

32

then KP = KC

when Dng > 0

then KP > KC

when Dng Keq then system proceed in backward direction

2

when n=2, then K¢¢C = K n=

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

(c)

E

(d)

1 3

to attain equilibrium. If Q < Keq then system proceed in forward direction 1/ 3

to attain equilibrium.

then K¢¢C = K

5

Aƒ B

KC =K1

B ƒC

KC = K2

CƒD

KC = K3 then

A ƒD

KC = K1 × K2 × K3

AƒB

KC = K1

2C ƒ 2B

KC = K2

DƒC

KC = K3 then

AƒD

KC =

K1 K2 * K3

Degree of dissociation (a)

a=

5

No. of moles of reactant dissociated No. of mole of reactant present initially

Degree of Dissociation from Vapour density n1A(g) ƒ n2B(g) + n3C(g) a=

n1 æ D T - D0 ö ç ÷ Dn g è D0 ø ; Dng =(n2 + n3)–(n1)

DT = theoretical vapour density =

Molecular weight of A 2

D0 = Observed vapour density

33

Chemistry HandBook

CHAP TER

ALLEN

PHYSICAL EQUILIBRIUM Physical reaction : Those reactions in which change in only & only physical states of substances takes place without any chemical change. (i)

Ice-water system (melting of ice) : Ice

(s) (more volume)

(ii) Water -Water vapour system (vapourisation of water) :

+ Heat ƒ water( l )

water

(l) (less volume)

(less volume)

It is an endothermic process & there is decrease in volume. Thus, the favourable conditions for melting of ice are high temperature, & high-pressure.

ƒ vapour( g)

(more volume)

It is an endothermic process & there is increase in volume. thus, the favourable conditions for vaporisation of water are high temperature, & lowpressure.

(iii) Solubility of gases in liquids : Gas(g) + water(l) ƒ Aqueous solution(l) It is an exothermic process, there is decrease in volume. thus, low temperature and high pressure will favour the dissolution of a gas in liquid. LE-CHATELIER’S PRINCIPLE If a system at equilibrium is subjected to a change of any one of the factors such as concentration, pressure or temperature then the equilibrium is shifted in such a way as to nullify the effect of change. Le-Chatelier’s principle is applicable for both chemical and physical equilibrium.

CHEMICAL EQUILIBRIUM

No. a)

b)

c)

d)

e)

34

Effect due to change in Concentration

Pressure

Temperature

Dissociation

Dng =0

Dng > 0

Dng < 0

AƒB

Aƒ2B

2AƒB

(i) ­ [A]

Forward direction

Forward direction

(ii) ¯ [A]

Backward direction

Backward direction

(i) ­ in pressure

Unchanged

Backward direction

(ii) ¯ in pressure

Unchanged

Forward direction

(i) ­ in Endothermic Forward direction

Forward direction

(ii) ­ in Exothermic Backward direction

Backward direction

Forward direction Backward direction Forward direction Backward direction Forward direction Backward direction

(i) ­ in pressure

Unchanged

Dissociation Decreases

Dissociation Increases

(ii) ­ in volume

Unchanged

Dissociation Increases

Dissociation Decreases Dissociation Decreases

Mixing of

(i) at constant P

Unchanged

Dissociation Increases

inert gas

(ii) at constant V

Unchanged

Unchanged

Unchanged

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

S.

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

35

Chemistry HandBook

CH APTER

ALLEN

IONIC EQUILIBRIUM ACID

BASE

Strong

Strong

Weak HClO3 HClO2 HClO H3PO4 H3PO2 H3PO3 H2S

H2CO3 HNO2 H2SO3 HCN H3BO3 HF Almost all organic acid Like : acetic acid oxalic acid

HClO4 HI HBr H2SO4 HCl HNO3

Weak

Group-1 hydroxide (except-LiOH) NaOH KOH RbOH Group-2 hydroxide except Be(OH)2 and Mg(OH)2 **Ca(OH)2 Sr(OH)2 Ba(OH)2

All other bases like NH4OH Zn(OH)2 Al(OH)3 Fe(OH)3 Cu(OH)2 etc.

ACID BASE THEORIES ARRHENIUS CONCEPT Acid :

Base :

Which produce H ion in aqueous solution.

which produce OH– ion in aqueous solution.

e.g. HCl, H2SO4, HClO4, H3PO4, CH3COOH

e.g. NaOH, Mg(OH)2, Ba(OH)2

+

Major Limitation :

but H3BO3 is not a Arrhenius acid.

Defined only in water solvent.

BRONSTED-LOWRY CONCEPT

Base : which accepts H+ in any solvent.

•

To find conjugate base of any Acid ® Remove one H+

•

To find conjugate acid of any Base ® add one H+

HCl + NH3 ƒ Cl A cid

B ase

—

C o nju g ate B ase

+ NH4

+

C o nju g ate A cid

•

Water is Amphiprotic solvent (can accept as well as lose H+)

H2O ƒ H++OH– H2O + H+ ƒ H3O+ Major Limitation : Does not explain acidic behaviour of aprotic acids e.g. SO2, SO3, CO2, AlCl3, SiCl4

36

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Acid : Which gives H+ in any solvent.

E

Chemistry HandBook

CH APTER

ALLEN

LEWIS THEORY BASE

ACID TYPES OF LEWIS BASE 1. Neutral molecule having lone pair

1.

Having Incomplete octet :

g g

2.

Having vacant d-orbitals: Having multiple bonds between atoms of different EN:

2.

CO, SO2, SO3 etc. 4.

Cations : Ag+, Li+, Al+3, Mg2+ false cations

gg

gg

gg

gg

H - O- H , R - O- R etc.

SF4, SF6,SnCl2, SnCl4 etc. 3.

(which cannot act as

Lewis acid) :

NH4+, H3O+, PH4+ etc.

Anions : O–2, SO42–, CO32–, Cl–, Br–, I–, CH3COO– etc. • All the Lewis bases are Bronsted bases but all the Lewis acids are not Bronsted acids. • All Arrhenius acids are Bronsted acid but it is not so for bases.

FOR PURE WATER

OSTWALD’S DILUTION LAW (Only for weak electrolytes)

1. [H+] = [OH–]

a µ dilution dilution ­Þ a ­

OSTWALD’S DILUTION LAW

EXPLANATION OF WATER H2O ƒ H+ + OH– Kw = Ionic product of water

2. pH = pOH

K

•

is always less than pH

= dissociation constant of water Kw = H O éëQ [ H2O] = 55.5ùû [ 2 ]

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

KW = [H+][OH—]

E

PKw 2 pH of an acidic solution

3. (PH)pure water =

pKw= pH + pOH K

g g

g g

N H3 , R - N H2 , R2 - NH ,

BF3, BCl3, B(OH)3, AlCl3 etc.

Lewis base is an electron pair donor

Lewis acid is an electron pair acceptor.

TYPES OF LEWIS ACID

of pure water. •

pH of an basic solution is always greater than pH of pure water.

DIFFERENT VALUES AT DIFFERENT TEMPERATURE At 25°C 1. Kw=10-14 2. (pH)pure water =(pOH)pure water =7 3. pH + pOH = 14

on increasing temperature Kw ­ on increasing temperature (pH)pure water decreases

At 90°C 1. Kw=10-12 2. (pH)pure water =(pOH)pure water =6 3. pH + pOH = 12

37

Chemistry HandBook

CHAPTER

ALLEN

pH OF DIFFERENT SOLUTIONS Type I : Single Substance CASE-1 Strong Acid : [H+] = NAcid+10–7

CASE-2 Strong Base: [OH–]=NBase+10–7(from

(from water)

water)

pH = – log [H+] We neglect smaller values (in Nacid + 10–7) if it is atleast 100 times smaller than other.

We can neglect smaller values. If it is atleast 100 times smaller than other. pOH = –log [OH–] pH = pKw –pOH

CASE-3 Weak acid : (for monobasic acid)

[ H+ ] =

CASE-4 Weak base: (for monoacidic base)

[OH- ] =

Ka C

Ka = dissociation constant of acid C : Initial concentation of acid

KbC

Kb = dissociation constant of base C : Initial concentration of base

Type II : More than one substances (Non-reacting CASE-5 : (SA)I + (SA)II

Initially same Beaker (If individual volumes are not given) +

[H ] = N1 + N2

CASE-6 : (SB)I + (SB)II

Same Beaker (Initially)

Initially in different beaker (Individual volumes are given) N1V1 + N2V2 + [H ] = V1 + V2

CASE-7 : SA + WA or SB + WB We can ignore [H+] / OH—

Different Beaker (Initially)

—

[OH ]=N1+N2 [OH—]=

coming from weak part as compared to strong part due to

N1V1 + N2V2 V1 + V2

common ion effect.

Type III : More than one substances (Reacting) + SB ® Salt of SASB + H2O Case 8 : NSA N2 V2 1V1

If N1V1 = N2V2

b)

Then salt of SASB is left in beaker after reaction.

If N1V1 > N2V2

c)

Then SA + salt of SASB is left in solution among which only SA is the contributing substance towards pH.

Salt of SASB : • Does not hydrolyse • Solution remain neutral (pH = 7 at 25°C)

[ H+ ] =

If N1V1 < N2V2 Then SB + salt of SASB is left in solution among which only SB is contributing substance towards pH.

N1V1 - N2 V2 V1 + V2

[OH- ] =

N2 V2 - N1V1 V1 + V2

+ SB ® Salt of WASB + H2O Case 9 : WA N1V1 N2 V2

a)

If N1V1 = N2V2 [ left :- salt of WASB]

b) If N1V1 > N2V2

Salt of WASB : Anionic hydrolysis

[left : WA+ salt of WASB] Acidic buffer

Þ Kh =

Kw ; h= Ka

Þ pH = 7 +

38

Kh C

1 [pK a + log C] 2

pH = pKa + log

( pH > 7 )

[ salt ] [ acid]

([C]in normality)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

a)

E

Chemistry HandBook

C H AP TE R

ALLEN

+ WB ® Salt of SAWB + H2O Case 10 : NSA N2 V2 1V1

a)

If N1V1 = N2V2 [left : salt of SAWB] Salt of SAWB : Cationic hydrolysis Kh =

Kw h= Kb ;

pH = 7 -

b)

+ WB ® Salt of WAWB + H2O Case 11 : WA N1V1 N2 V2

If N1V1 = N2V2 [left : salt of WAWB] Salt of WAWB : Cationic anionic or anionic cationic hydrolysis

Kh C

Kh =

1 [ pK b + log C ]; 2

[ pH < 7]

pH = 7 +

If N1V1 < N2V2

1 [pKa - pKb ] 2

pH & h is independent of ‘C’.

[left : WB + salt of SAWB] basic buffer æ [ salt ] ö pOH = pKb + log çè [ base ] ÷ø

Kw ; h = Kh Ka × Kb

[pH can > 7, < 7 or = 7 depends on value of Ka & Kb]

SOLUBILITY(s) & Solubility Product (Ksp) Solubility :

Ionic Product [Qsp]

The maximum amount of solute that can be dissolved in a particular amount of solvent at a given temperature is called solubility(s). It is generally expressed in molarity.

AxBy ƒ xA+y + yBx– ; Qip = [ A y + ] [ B x - ]

AgCl ( s )

ƒ AgCl ( aq) ®

Ag+ + Cl -

dissociation

dissolution

AgCl ƒ Ag + Cl Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

E

In Qip the concentration taken are at any time but in Ksp the concentration are at equilibrium time / saturation time. Applications : 2. If Qip = Ksp [ saturated]

–

3. If Qip > Ksp [super saturated / ppt. will form]

Ksp = [Ag ] [Cl ]

Effect of common ion

depends only on temperature.

•

+

y

1. If Qip < Ksp [ unsaturated]

Solubility Product (Ksp): +

x

–

Expressions of Ksp : AxBy ƒ xA+y + yBx– x

y

General form Ksp = [ Ay + ] [ Bx- ]

In terms of ‘S’ : Ksp = ( xS ) x ( yS ) y

Presence of common ion decreases the solubility but has no effect on Ksp as it depends only on temperature.

Effet of odd ion •

Presence of odd ion increases the solubility but has no effect on Ksp.

39

Chemistry HandBook

CH APTER

Group

Radicals

ALLEN

Condition for

Forms of

precipitation

precipitation

(Group reagent) Zero

Na+,K+, NH +4

First

Pb , Hg ,

By mixing of

Chloride

( Hg ) , Ag+

dilute HCl

AgCl, Hg2Cl2, PbCl2

Pb+2, Cu+2, Hg+2, Cd+2, Bi+3, As+3, Sb+3, Sn+2,Sn+4

H2S gas passed in the presence of acidic medium

Sulphide PbS,HgS, CuS,CdS, SnS, SnS2 ,As2S3, Sb2S3 , Bi2S3

Third

Al+3, Cr+3, Fe+3

NH4OH mixed in the presence of NH4Cl

Hydroxide Al(OH)3, Fe(OH)3 Cr(OH)3

Fourth

Zn+2, Ni+2, Mn+2,Co+2

H2S gas passed in presence of

Sulphide MnS, CoS,

basic medium

NiS, ZnS

1-2 drops of

–

CH3 COOH +1

+2 2

Second

Fifth

Ba+2, Sr+2, Ca+2

(NH4)2 CO3 mixed in the presence of NH4Cl

Carbonate BaCO3, SrCO3, CaCO3

Sixth

Mg+2

By mixing of Na2HPO4

Hydrogen phosphate (MgHPO4)

Name of indicator

Colour

Colour

Working

in acidic

in basic

pH range

medium

medium

of indicators

KEY POINTS

Methyl orange (MeOH)

Pinkish red

Yellow

3.1 to 4.5

Methyl red

Red

Yellow

4.2 to 6.2

O

Phenol red

Yellow

Red

6.2 to 8.2

Buffer capacity

Phenolphthalein (HPh)

Colourless

Pink

8.2 to 10.2

=

No. of moles of H+ /OH - added per litre change in pH of buffer solution

O

ACID-BASE TITRATION Type of

pH range of

Suitable

titration

titration

indicators

Maximum buffer action when [salt] = [acid]

3 – 11

All indicators

O

SA/SB.

(MeOH, HPh etc.) SA/WB

3–7

Methyl orange (MeOH) and methyl red

WA/SB

7 – 11

Phenolphthalein (HPh)

WA/WB

40

6.5 – 7.5

Phenol red

pH of Amphiprotic species :(NaH2PO4, NaHCO3) which can donate as well as accept H+ pH=

pK a1 + pKa2 2

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

+2

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

41

Chemistry HandBook

CH APTER

ALLEN

SOLID STATE DEFECTS STOICHIOMETRIC DEFFECT Schottky Equal no. of cation & anion are missing from their respective sites.

IMPURITY DEFECT

Frenkel Smaller ion leaves its appropriate site & occupies an interstitial site.

NON-STOICHIOMETRIC DEFFECT

CORNERS FACES EDGES BODY CENTRE BODY DIAGONAL FACE DIAGONAL FACE CENTRES EDGE CENTRES

Metal Deficiency Defect Eg. Fe0.93O to Fe0.96O Metal excess defect due to the presence of extra cation at interstitial site.

8 6 12 1 4 12 6 12

Metal excess defect due to anionic vacancies (anion is absent from its site which is occupied by an electron). This site is called F-centre. Limiting Radius Ratio

Coordination No. of cation

Geometry of Void

0.155 £ r/R < 0.225

3

Plane Trigonal

0.225 £ r/R < 0.414

4

Tetrahedral

FCC, HCP

0.414 £ r/R < 0.732

6

Octahedral

FCC, HCP

0.732 £ r/R < 1.000

8

Cubical

SC

Void found in

Location of void

No. of void per atom

Example Boron oxide (B2O3)

2

ZnS, SiO2, Na2O, CaF2

Body centre & edge centres

1

NaCl, MgO

Body centre

1

CsCl

Classification of solid on the basis of nature of order of arrangement of constitutent particles These solids have definite characteristic shape Definite melting point & heat of fusion Cleavage surfaces are smooth Anisotropic in nature. Long range order. Ex. : NaCl, Quartz, Metal, Diamond etc.

42

AMORPHOUS These solids have irregular shape. Indefinite melting point & heat of fusion. Cleavage surface are irregular. Isotropic in nature. Short range order. Ex. Glass, Quartz Glass, Rubber, Plastics etc.

Name of system

Axis

Angles

1. Cubic 2. Tetragonal 3. Orthorhombic or Rhombic 4. Monoclinic 5. Triclinic 6. Rhombohedral or Trigonal 7. Hexagonal

a=b=c a=b¹c a¹b ¹c a¹b ¹c a¹b ¹c a=b=c a=b¹c

a=b=g=90° a=b=g=90° a=b=g=90° a=g=90°, b ¹ 90° a ¹ b ¹ g ¹ 90° a=b=g ¹ 90° a=b=90°, g=120°

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

CRYSTALLINE

E

S. No.

Type of Ionic Crystal NaCl (1:1) (Rock salt Type)

1.

Chemistry HandBook

CHAPTER

ALLEN

Geometry

Coordination Number

No. of formula per U.C.

6:6

4Na + 4Cl 4NaCl (4)

—

Cl : Every lattice point of CCP CCP + Na : At Every OHV

+

—

Examples l l l

CsCl Type (1 : 1)

2.

3.

ZnS Type (1:1) (Zinc Blende Type) (Sphalerite)

4.

CaF2 Type (1:2) (Fluorite Type)

Na2O Type (2:1) (Antifluorite Type)

5.

ZnS Type (1:1) (Wurtzite) another geometry of ZnS

6.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

S. No.

E

Contents

1.

Geometry

2.

Arrangement

3.

-2

S : Every lattice point of CCP CCP +2 Zn : At 50% of THV or At Alternate THV Ca+2 : Every lattice point of CCP CCP — F : At every THV

1Cs+ + 1Cl— 1CsCl (1)

8:8

Cl— : At Every Corner BCC Type + Cs : At Body centre

+

—2

O : Every lattice point of CCP

—2

4O

: 8

4

—2

S : Every lattice point of HCP HCP +2 Zn : 50% of THV or at alternate THV SC

+2

—1

BaCl2, BaF2, SrCl2, SrF2, CaCl2, CaF2

+

—2

Li 2O, Li2S, Na2O, Na2S, K2O, K2S

+2

—2

Same as Sphalerite

4Ca + 8F 4CaF2 (4)

8Na

CCP

BeS, BeO, CaO, AgI CuCl, CuBr, CuI

4Ca+2 8F—

+

Na : At every THV

4:4

BCC

Halides of 'Cs' TlCl, TlBr, CaS

—2

4Zn + 4S 4ZnS (4)

: 4

l

+2

4:4

8

l

Halides of (Li, Na, K, Rb); Oxides & sulphides of Alkaline earth metals; (some exception) AgF, AgCl, AgBr, NH4X

8Na + 4O 4Na2O (4) 6Zn + 6S 6ZnS (6)

FCC/CCP

HCP

AAAA... Packing close packing

ABAB... Packing but not close packing

No. of atoms per UC

1

2

4

6

4.

Coordination No.

6

8

12

12

5.

a & r relation

r = a/2

r =aÖ3/4

r =a/2Ö2

6.

Packing Efficiency

p/6 or 52.4%

pÖ3/8 or 68%

p/3Ö2 or 74%

7.

Example

Mn

IA ; Group:V&Cr; Ba, Fe

ABCABC... Close Packing

ABAB... Close Packing

p/3Ö2 or 74% Remaining d-block elements, Be & Mg

43

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Chemistry HandBook

44 ALLEN

IMPORTANT NOTES

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

45

Chemistry HandBook

CH APTER

ALLEN

SURFACE CHEMISTRY Classification based on interaction of phases :-

LYOPHILIC AND LYOPHOBIC SOLS

Colloidal solutions in which the dispersed phase has considerable affinity for the dispersion medium, are called lyophilic sols (liquid – loving). For example - dispersion of gelatin, starch, gum and proteins in water. Colloidal solutions in which the dispersed phase has no affinity or attraction for the dispersion medium are called Lyophobic colloidal (liquid hating) solutions. COMPARISION OF LYOPHOBIC AND LYOPHILIC SOLS Lyophilic sol (Emulsoid)

Lyophobic sol (suspensoid)

1. Preparation

Can be easily prepared by shaking or warming the substance with liquid

Can not be prepared easily, special methods are required

2. Stability

are more stable

are less stable

3. Reversibility

are reversible

are irreversible

4. viscocity

viscocity is much higher than that of

viscocity is nearly same as that of the

dispersion medium

dispersion medium

5. Surface tension Surface tension is usually low 6. Hydration or solvation 7. Charge

Surface tension is almost same as that of dispersion medium

These are highly solvated as the particles

These are less solvated as the particles have less

have great affinity for solvent

affinity for the dispersion medium

The particles have little charge or no

The particles carry a characteristic charge

charge at all

either positive or negative

8. Visibility

Particles can not be seen under microscope

Particles can be seen under microscope

9. Tyndall effect

Less Scattering

More Scattering

10. Migration in electric field 11. General Ex.

PE

ON TI A IZ PT

may or may not migrate as they may

migrate towards anode or cathode as these

or may not carry charge.

particles carrry charge.

Mostly of organic nature

Mostly of Inorganic nature

Ex. Gelatin, Starch,

Ex. Transiton metal salt in water like

Gum, Albumin & Cellulose Solution

Gold, As etc.

The dispersion of a freshly precipitated material into colloidal solution by the action of an electrolyte in solution is termed as peptization. The electrolyte used is called a Peptizing agent. Hardy Schulze Rule - This rule states that the precipitating effect of an ion on dispersed phase of opposite charge increases with the valency of the ion. The higher the valency of the flocculating ion, the greater is its precipitating power. Thus for the precipitation of As2S3 sol (–ve) the precipitating power of Al3+, Ba2+, and Na+ ions is in the order Al3+ > Ba2+ > Na+ Similarly for precipitating Fe(OH)3 sol (positive) the precipitating power of [Fe(CN)6]–3, SO42– and Cl– ions is in the order [Fe(CN)6]3–

>

SO42–

>

Cl–

The minimum concentration of an electrolyte in milli moles required to cause precipitation of 1 litre sol in 2 hours is called FLOCCULATION VALUE. The smaller the flocculating value, the higher will be the coagulating power of the ion.

Flocculation value a

46

1 Flocculation power

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Property

E

Chemistry HandBook

CHAPTER

ALLEN

The number of milligrams of a protective colloid (lyophillic colloid) that will just prevent the precipitation of 10 ml of standard gold sol on addition of 1 ml of 10% NaCl solution is known as Gold number of that protector (Lyophilic colloid).

GOLD NUMBER

The precipitation of the gold sol is indicated by a colour change from red to blue when the particle size just increases. The smaller the gold number of a protective Lyophilic colloid, greater is its protection power. Note : Gelatin and startch have the maximum & minimum protective powers respectively.

Protection Capacity a

1 Protection Number (Gold number)

TYPES OF COLLOIDS ACCORDING TO THEIR SIZE Multi Molecular

Macro Molecular

Associated colloids

Formation by aggregation of a large number of atoms or smaller molecules of substance.

Macromolecules in suitable liquid form colloid solution in which size of macro molecules may be in colloidal rang. These are polymers with high molecular mass.

Ex. ® Gold Sol (Au) Sulphur sol (S8)

Ex. ® Starch, Cellulose, Protein etc.

These are the substances which behave as normal electrolytes at low concentration but get associated at higher concentration and behave as colloidal solutions. These associated particles are also called micelles. Ex. ® Soap & Detergent

E

Physical Adsorption

Chemical Adsorption (Activated ad.)

1.

It is caused by intermolecular vander waal’s forces.

It is caused by chemical bond formation.

2.

It is not specific.

It is highly specific.

3.

It is reversible.

It is irreversible.

4.

Heat of adsorption is low. – 20 to –40 KJ/mol

Heat of adsorption is high. –80 to –240 KJ/mol

5.

No appreciable activation is energy is involved.

High activation energy involved.

6.

It forms multimolecular layers on adsorbent surface.

It forms unimolecular layer under high pressure.

C H G A E R N A E C R C AT O TER AL A F IS LY TI ST C S S

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

COMPARISON OF PHYSI-SORPTION AND CHEMI-SORPTION

(i)

(ii) (iii) (iv) (v)

Critical temperature increases Ease of liquification increases Extent of adsorption increases (true for physisorption)

A catalyst remains unchanged in mass and chemical composition but can change their physical state. Only a very small amount of catalyst is sufficient to catalyse a reaction. A catalyst does not initiate a reaction. Solid catalyst is more efficient when used in finely divided form. Generally catalyst does not change the nature of products.

(vi)

(vii) (viii) (ix) (x)

A catalyst does not change the equilibrium state of a reversible reaction but helps to achieve the equilibrium state or position of equilibrium in lesser time. The catalyst are generally specific in nature. Changes rate constant of reaction. Does not change free energy of reaction and enthalpy of reaction. Participate in mechanism of reaction.

47

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\1_PHYSICAL.P65

Chemistry HandBook

48 ALLEN

IMPORTANT NOTES

E

INORGANIC CHEMISTRY

Chemistry HandBook

CHAP TER

ALLEN

Some Important Increasing Order 1. Acidic property (i) SiO2, CO2, N2O5, SO3 (ii) MgO, Al2O3, SiO2, P4O10 (iii) HClO, HClO2, HClO3, HClO4 (iv) CH4, NH3, H2O, HF (v) SiH4, PH3, H2S, HCl (vi) H2O, H2S, H2Se, H2Te (vii) HF, HCl, HBr, HI (viii) lnCl3, GaCl3, AlCl3 (ix) BF3, BCl3, BBr3, BI3 (ii) H2O, NH3, CH4, CO2 (iv) NO2—, NO2, NO2+ (vi) AsH3, PH3, NH3 (viii) NF3, NCl3 (x) OF2, OH2, Cl2O

2. Basic Character (i) LiOH, NaOH, KOH, RbOH, CsOH (ii) Be(OH)2,Mg(OH)2,Ca(OH)2,Ba(OH)2 (iii) BeO, MgO, CaO, SrO (iv) NiO, MgO, SrO, K2O, Cs2O (v) CO2, B2O3, BeO, Li2O (vi) SiO2, Al2O3, MgO, Na2O (vii) SbH3, AsH3, PH3, NH3 (viii) F—, OH—, NH2—, CH3—

ù (i) Li2CO3, Na2CO3, K2CO3, Rb2CO3, Cs2CO3 ú (ii) BeCO3, MgCO3, CaCO3, BaCO3 ú (iii) Be(OH)2, Mg(OH)2, Ca(OH)2, Sr(OH)2,Ba(OH)2ú Polarisation

ú ú úû

5. Solubility (i) BaCO3, CaCO3, MgCO3, BeCO3 (ii) Be(OH)2, Mg(OH)2, Ca(OH)2, Ba(OH)2 (iii) BaSO4, SrSO4, CaSO4, MgSO4, BeSO4 (iv) Li2CO3, Na2CO3, K2CO3, Rb2CO3, CsCO3 (v) LiOH, NaOH, KOH, RbOH, CsOH (vi) LiF, LiCl, LiBr, LiI (vii) LiF, NaF, KF, RbF, CsF (viii) BaF2, SrF2, MgF2, CaF2, BeF2 (ix) CaF2, CaCl2, CaBr2, Cal2 (x) AgI, AgBr, AgCl, AgF ù 1 ú Solubility µ covelent char. (xi) PbO2, Cdl2, RbI û

50

(i) Mg2+, Na+, F–, O2–, N3– (Hint : Isoelectronic series) (ii) Ca2+, Ar, Cl–, S2– (iv) B, Be, Li, Na

(iii) O, C, S, Se (v) F, O, F–, O2–

8. Oxidizing Power (ii) MnO42–, MnO4– (i) Cr2O72–, MnO4– (iii) WO3 , MoO3, CrO3 (iv) GeCl4, SnCl4, PbCl4 (v) I2, Br2, Cl2, F2 (vi) Zn+2, Fe+2, Pb2+, Cu2+, Ag+

4. Thermal Stability

(iv) LiOH, NaOH, KOH, RbOH, CsOH (v) BeSO4, MgSO4, CaSO4 (vi) CsH, RbH, KH, NaH, LiH (vii) SbH3, AsH3, PH3, NH3 (viii) H2Te, H2Se, H2S, H2O (ix) HI, HBr, HCl, HF

7. Atomic / Ionic Size

9. Ionization Energy (i) Na, Al, Mg, Si (ii) Li, B, Be, C, O, N, F, Ne, He (Ist I.P.) (iii) Be, C, B, N, F, O, Ne, Li, He (IInd I.P.) 10. Melting Point (i) Cs, Rb, K, Na, Li (ii) Mg, Ba, Sr, Ca, Be (iii) CaI2, CaBr2, CaCl2, CaF2 (iv) BeCl2, MgCl2, CaCl2, SrCl2, BaCl2 (v) NaI, NaBr, NaCl, NaF (vi) CsCl, RbCl, KCl, NaCl (vii) AlCl3, MgCl2, NaCl 11. Density (i) Na, Al, Fe, Pb, Au (ii) Li, K, Na, Rb, Cs (iii) Ca, Mg, Be, Sr, Ba (iv) Highest Density = Os/Ir (v) Lowest density = H (vi) Metal of lowest Density = Li

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

2. Bond Angle (i) CH4, C2H4, C2H2 (iii) H2O, NH3, CH4, BH3 (v) H2Se, H2S, H2O (vii) PF3, PCl3, PBr3, PI3 (ix) NF3, NH3, NCl3

6. Ionic Character (i) LiBr, NaBr, KBr, RbBr, CsBr (ii) LiF, NaF, KF, RbF, CsF (iii) BeCl2, MgCl2, CaCl2, SrCl2, BaCl2 (iv) BCl3, AlCl3, GaCl3 (v) VCl4, VCl3, VCl2 (vi) AlF3, MgF2, NaF (vii) AlN, Al2O3, AlF3 (viii) HI, HBr, HCl, HF (ix) CuCN, AgCN (x) AgCl, KCl

E

12. Boiling Point (i) PH3, AsH3, NH3, SbH3 (iii) HCl, HBr, HI, HF (v) He, Ne, Ar, Kr (vii) H2, Cl2, Br2 13. Reactivity with water (i) Li, Na, K, Rb, Cs

(ii) H2S, H2Se, H2O (iv) NH3, HF, H2O (vi) H2O, D2O

(ii) Be, Mg, Ca, Sr, Ba

14. Extent of Hydrolysis (i) CCl4, MgCl2, AlCl3, SiCl4, PCl5 (ii) BiCl3, SbCl3, AsCl3, PCl3, NCl3 15. Bond Strength (i) HI, HBr, HCl, HF (ii) – C – I, – C – Br, – C – Cl, – C – F N – N, N = N, N º N As – H, Sb – H, P – H, N – H N22–, N2–, N2+, N2 O22–, O2–, O2 , O2+, O22+ LiI, LiBr, LiCl, LiF NaI, NaBr, NaCl, NaF CsCl, RbCl, KCl, NaCl BaO, SrO, CaO, MgO (vii) F2, H2, O2, N2 (viii) NO–, NO, NO+ (ix) I2, F2, Br2, Cl2 (x) O–O, S– S (xi) F – F, O – O, N – N, C – C, H – H (iii) (iv) (v) (vi)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

16. Reducing Power (i) PbCl2, SnCl2, GeCl2 (iii) Ag, Cu, Pb, Fe, Zn (v) H3PO4, H3PO3, H3PO2

E

Chemistry HandBook

CHAP TER

ALLEN

(ii) HF, HCl, HBr, HI (iv) HNO3, H2SO3, H2S

17. Covalent Character (i) LiCl, BeCl2, BCl3, CCl4 (ii) SrCl2, CaCl2, MgCl2 (iii) TiCl2, TiCl3, TiCl4 (iv) LiCl, LiBr, LiI (v) Na2O, Na2S (vi) AlF3, Al2O3, AlN (vii) HF, HCl, HBr, HI 18. Strength of Hydrogen bonding (X...H–X) (i) S, Cl, N, O , F (ii) NH3, H2O, HF 19. Ionic Radii in water (i) Cs+, Rb+, K+, Na+, Li+ (ii) Li+, Be+2 (iii) Na+, Mg+2, Al+3

21. Reactivity with Hydrogen (i) Cs, Rb, K, Na, Li (ii)Ba, Sr, Ca, Mg, Be 22. Reactivity Towards Air Be, Mg, Cs, Sr, Ba 23. Hydration of Ions/Hydration Energry (i) Ba+2, Sr+2, Ca+2, Mg+2, Be+2 (ii) Cs+, Rb+, K+, Na+, Li+ (iii) Na+, Mg+2, Al+3 24. Electron Affinity (i) I, Br, F, Cl (ii) Cu, Ag, Au (EA, of Au is very high = 222 kJ mol–1) (iii) O, S, F, Cl (iv) N, P, O, S 25. Electonegativity (i) As, P, S, Cl

(ii) I, Br, Cl, F

26. Bond Length (i) N2, O2, F2, Cl2 (iii) CO, C=O, –C–O–

(iii) C, N, O, F

(ii) NºN, CºN, CºC (iv) NO+, NO, NO—

(v) O2, O3, H2O2 (O-O bond length) (vii) N2, N2–, N2–2 (vi) CO, CO2, CO3–2 –2 – +2 (ix) HF, HCl, HBr, HI (viii) O2 , O2, O2, O2 27. Dipole moments (i) CCl4, CHCl3, CH2Cl2, CH3Cl (ii) NF3, NH3, HF, H2O (iii) Cis-chloropropene, Trans-chloropropene (iv) p, m, o-dichlorobenzene (v) CH3I, CH3Br, CH3F, CH3Cl (vi) NH3, SO2, HF, H2O (vii) H2S, H2O (viii) HI, HBr, HCl, HF (ix) PH3, ASH3, SbH3, NH3 (x) H2O, H2O2 28. Abundance of Elements (i) Elements on earth crust (ii) Metals on earth crust (iii) Non-metals In atmosphere In universe

- Fe, Al, Si, O - Ca, Fe, Al - Si, O - O, N - He, Si, H

20. Molar Conductivity in Water Li+, Na+, K+, Rb+, Cs+

51

52

Atomic radius Ionisation potential Electronegativity Electron affinity Covalent character of halides Metallic character Increases Oxidising nature Decreases Reducing nature Decreases Screening effect Decreases Effective nuclear charge (Zeff) Decreases Valency w.r.t. oxygen Increases Basic character of hydrides Decreases Basic character of oxides Increases Basic character of oxy acids Increases Strenth of oxy acids Constant Thermal stability of sulphate Constant Thermlal stability of carbonates (Metals)Increases Thermal stability of nitrates (Non metal) Decreases (Metals)Increases Thermal stability Increases of hydroxide Decreases Increases Density Increases Electro positivity Increases Increases Increases Increases

PERIODS

CHAP TER

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

GROUPS

First increass then decreases Decreases

Decreases Increases Increases Increases Increases Decreases Increases Decreases Increases Increases Increases Decreases Decreases Decreases Increases Decreases Decreases Decreases Decreases

GENERAL TREND OF DIFFERENT PROPERTIES IN THE PERIOD AND GROPUS

Chemistry HandBook ALLEN

Some Important Increasing Order

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

ALLEN

E CH APTER

Chemistry HandBook

PERIODIC TABLE

53

Chemistry HandBook

C HAP TE R

ALLEN

MENDELEEV'S PERIODIC TABLE Base chemical properties of elements. Like : reaction with O2, H2 & X2 Mendeleev's Periodic Law Physical & chemical properties of elements are periodic function of their atomic weight

Prout's Hypothesis Dobernier's triad Newlands law of octave

8 Groups & 7 period

Lother meyer curve

Left some vacant position for some elements. eka-boron - Sc eka-Aluminium-Ga

MOSELEY x-ray EXPERIMENT zµn Modern Periodic law Physical & chemical properties of the elements are periodic function of their atomic numbers. Introduced zero group for Nobel gases.

eka-managanse-Tc eka-silicon-Ge

(a) Bohr classification

(iv) Inert gases :

(i)

18 group He, Ne, Ar, Kr, Xe Rn Do not use any electron during chemical combination (b) On the basis of conductivity

Normal / representative elements s & p block (except inert gas) 1-2 1—5 ns np ; use electrons only valence shell during chemical combination. (ii) Transition elements d-block : use electrons of n shell as well as (n—1) shell during chemical combination. Zn, Cd & Hg are not transitional elements. (iii) Inner transition elements f-block : use electrons of n shell (n-1) shell and (n-2) shell

Metal ®conductor Metalloid ®semi-conductor Non-metals®Non-conductor (c) On the basis of physical state Solid (rest) Liquid (6): Br, Ga, Hg, Uub, Cs, Fr Gas (11): He, Ne, Ar, Kr, Xe, ln, F, Cl, O, N, H

POSITION OF ELEMENTS IN PERIODIC TABLE Period : Highest number of shell, which contain electron. Block : Highest energy sub-shell which contain electron. ns < (n-2) f < (n-1)d < np Group No. : depends on block (a) s-block : Number of ns electron's (b) p-block : Number of np electron's +12 (c) d-block : Number of ns + (n-1)d electron's rd

(d) f-block : 3 or IIIB group.

54

Eg . : Atomic n umber 5 3: [Kr] 5s 2 10 5 4d 5p Period-5 Block-P Group- 1 2+5= 17

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

DEVELOPMENT OF PERIODIC TABLE

E

Chemistry HandBook

CH APTER

ALLEN

PERIODICITY

SCREENING EFFECT / SHIELDING EFFECT

Repetition of properties after regular

H

interval is known as periodicity and these properties are known as periodic properties. 1. Effective nuclear charge (Z eff) 2. Atomic Radius 3. Ionisation potential 4. Electron affinity 5. Electro negativity

Repulsive force applied by inner electron on a particular electron / last electron / tested electron. Calculation of screening (s)- by Slater's Rule. Z s by test electron = 0.00 Z s by rest of valence electron = 0.35 Z s by (n-1) s,p ®0.85 Z s by (n-2) or inner electrons = 1.0 Varation of s ® along the periodic & down the group increases. Order of s : s > p > d > f

ATOMIC RADIUS Distance between centre of nucleus to outermost electron.

H Effective nuclear charge (Zeff) Zeff = Z—s

PERIODIC TRENDS

Accurate value of atomic radius cannot be measured. We measure internuclear distance and assume half of it as atomic radii.

group T ¯ B AR­

On the basis of type of bond atomic radii is of following type : Single bonded species rmetallic

rcovalent A

A

A

rcov =

dA—A 2

A

A

rmetallic=

rvanderwaal

dA—A 2

* Al ; Ga : Transition Contraction

rvanderwaal's = dA—A 2

* 4d ; 5d : Lanthanide Contraction d-block

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

E

ION

IC

RA D

» » » » » » » » » » »

1 Zeff

1 bond strength

(b) Different series (generally) — — — — — 2e < 10e < 18e f (applicable in neighbor atom)

5 6

th

Factor 5 & 6 applicable upto 4 period only Be > B Sb < Te N>O

PER IODICITY

Period IP­ L-R group T ¯ B IP¯

OF

IP

Metallic character µ

1 IP

Reactivity of metal µ

1 IP

Electro+ve character µ

1 IP

Reducing naturer µ

1 IP

atom

anion -energy

Amount of energy released or absorb when an electron added to neutral gaseous atom. -

x(g) + e ® x (g) —

—

No. of valance e = consider successive IP highest jump in successive IP indicate nobel gas configuration if it is 'a' then no. of valence e— — valence e = a—1 Consider successive IP STABILITY OF (a) If DIP ® < 11 eV higher o.s. stable STATE TION OXIDA DIP ® > 16 eV lower o.s. stable

56

+e—

Generally Exothermic If we measure energy in term of energy change it is known as electron gain enthalpy. DHeg = final state - initial state (anion) (atom)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

APPLICATION

E

FACTORS E.A. µ Zeff E.A. µ 1 size Electron configu ration : Stable valen ce sh ell configuratio n of electron gaining would be a endothermic higher the stability of configuration higher endother mic process of elec tron gaining or der Be N Ne 2s 2 2s22p 3 2s 22p 6 order Ne < Be < N of EA max endo least endo

re than one e ; these When an atom gain mo ssive electrons and ce suc s K/a electrons are cessive electron affinity. their energy is K/as suc II — I 2— +e — x — x ener gy x + e energy —

EA 2

EA 1

othermic due to EA2 or higher always end incoming electron. & on repulsion between ani

in p-block B ^ Al

Chemistry HandBook

CHAPTER

ALLEN

PERIODICITY

®EA­ e­ DHeq -v ¯ EA¯ DHeq -ve ¯

EXCEPTIONAL POINT

ELECTRONEGATIVITITY

EA of 2nd period < 3rd period

Tendency of an atom to attract shared pair of electron towards itself in bonded state is known as electronegativity. ® Relative Phenomenon. ® Unit less property. ® For Nobel gas we consider EN = zero.

C ^ Si

N ^ P

O ^ S

F ^ Cl

Maximum EA 'Cl' O has least in it's group.

RELATIONSHIP BETWEEN IP & EA +e ; EA —

—

m

+

IP of M = EA of M+

x

+e ; EA —

EA of x = IP of x—

E

Non-polar bond DEN = 0 Polar bond

DEN ¹ 0

Exception : Zn < Cd < Hg Ga < In < Tl

CT

RO

A E L E PP L I C

Period L-R EN­

Bond & Bond properties

DEN­® Bond polarity ­ ¯ Bond length ¯ ¯ Bond strength ­ ¯ Ionic character ­

Bond length - Sehumaker stevension formula = d A-B = r A + rB - 0.09 × DEN

O XIDES & HYDROXIDES

N ATURE OF C OMPOUNDS

% age ionic character : Hennay -Smith formula = 16 × DEN + 3.5 (DEN) Acidic character µEN 1 Basic character µ EN

2

Electro negativity ­® Acidic character of oxide ­ Basic character of oxide ¯ s-block hydride - Metallic hydride, basic character µ size P-block hydride - Non metallic hydride, acidic character µ size

HYDRIDES

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

PERIODIC TRENDS

group T ¯ B EN¯

—

x

-e ; IP

AT IO N O NE GA F T IV I TY

-e ; IP —

M

57

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Chemistry HandBook

58 ALLEN

IMPORTANT NOTES

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

59

Chemistry HandBook

CHAPTER

ALLEN

CHEMICAL BONDING CHEMICAL BONDING Force of attraction which holds two or more than two species together is known as bond. H—H

H2O

REASON To attain the state of maximum stability, species have tendency of bonding.

+

H2O

Na

Cl

—

CLASSIFICATION OF BONDS On the basis of type of species getting bonded bonds can be classify into following categories. BOND Intermolecular force between molecules weak bond 2-40 kJ/mol

Interatomic bond between two atom strong bond 200 - 400 kJ/mol

Non-metal + Non-metal - covalent bond H-bond

Non-metal + Metal - Ionic bond

1. Ion-dipole 2. Dipole-Dipole 3. Ion-Induced dipole 4. Dipole-Induced dipole 5. London force

Metal + Metal - Metallic bond Coordination bond is type of covalent bond

Formation of covalent bond explained by three theories. Valence Bond Theory

Molecular Orbital Theory

LEWIS OCTET THEORY

VALENCE BOND THEORY

As per Lewis Octet Theory Bonding for Stability Stability by achieving Nobel gas configuration.

Atoms undergoes sharing of electron. Sharing of electron leads to the formation of covalent bond.

VALENCE B OND THEORY Sharing

60

Equal sharing - Covalent Bond Unequal sharing- Coordinate Bond

H2

Cl2

O2

HNO3

H H

Cl Cl

O O

H—O—N

H—H

Cl—Cl

O=O

O O

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Lewis Octet Theory

E

Chemistry HandBook

C HAP TE R

ALLEN

EXCEPTION (a) electron deficient Central atom: No. of electron < 8 BeH2 BF3, BCl3, BBr3, BI3 AlCl3, AlBr3, AlI3

OF

OCTET RULE

(b) electron rich Central atom: No. of electron > 8 PCl5 , IF7 SF6, XeF2

(c) odd electron species Central atom : has odd electron NO, NO2, ClO2 ClO3

CO-ORDINATE BOND (DATIVE BOND) In this type of bond, shared pair of electron donates by one species but shared by both For this type of sharing One species - must have lone pair - act as donar known as Lewis base - acquire +ve charge. Another species - must have vacant orbital act as acceptor known as Lewis acid - acquire -ve charge.

LB

LA

+

N

y

+

+

H

rl

H H H

ila

N+H

+

m

H H H

Si

Eg.

H2O + H

H3O

+

+

N2H4+H

N2H5

AlCl3 + AlCl3

Al2Cl6

Donor atom follow octet rule

MODERN APPROACH OF COVALENT BOND Consider wave mechanical model of atom means electron has dual nature; wave nature as well as particle nature considered by these theories, there are two theories in this approach. 1. Valence Bond Theory

VALENCE BOND THEORY Proposed by Heitler & London as per VBT bonding takes place for attaining stability. 1 Stability µ Potential energy

2. Molecular Orbital Theory Only those orbitals of valence shell can exhibit overlapping which has Unpaired electron

attraction > repulsion

Opposite spin

E

native state of atom

energy

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

+ve

AF > RF

-ve

AF > RF

Attraction=Repulsion [Min. potential energy state]

Strength of Covalent Bond Strength of covalent bond µ extent of overlapping. 1. NATURE OF ORBITALS (a) No. of shell : lower the number of shell higher overlapping.

distance

Bond formation is an exothermic process. During this process some extent of electron cloud merge into each other; this part is known as overlapped region & this process is known as overlapping. Atom

For example H—Cl bond form by overlapping of 1s - 3p orbitals. 1 H® 1s 2 2 6 2 5 Cl® 1s 2s 2p 3s 3p

Nucleus Shell - subshell - orbital - electron - cloud

Bond Strength µ

1 /size of orbitals No. of shell

1-1 > 1-2 > 2-2 > 2-3

Exception : Cl2 > Br2 > F2 > I2 O—O < S—S N—N < P—P

due to lp-lp repulsion

61

Chemistry HandBook

CHAPTER

ALLEN

(b) Type of Sub-shell Valence shell contain subshell s & p s-non-directional p-directional

s-s < s-p < p-p

Directional orbital has higher extent of overlapping

** This factor is applicable when number of shell is same otherwise shell factor prominent 2s - 2s < 2s-2p < 2p-2p sub-shell factor 1s - 1s > 1s-2s > 1s-3s shell factor

2. P ATTERN OF OVERLAPPING (a) Axial overlapping : Along the internuclear axis; form sigma (s) bond, strong bond.

(b) Co-lateral overlapping Side wise overlapping has less extent of overlapping form p- bond Weak bond

s-s

p-p overlapping

Internuclear axis pp-pp pi-bond

s-p

p-d overlapping

p-p

pp-dp pi bond

In case of multiple bond between two atom one bond is sigma and rest are pi-bonds. VBT was not able to define geometry of molecule therefore a new concept came into existence known as hybridisation.

HYBRIDISATION Intermixing of atomic orbitals and formation of new orbital, these orbitals are known as hybrid orbital and this concept is known as hybridisation. It is hypothetical concept. Only those orbitals can participate in hybridisation which has slight difference in energy.

S.No. Type of orbital

62

No. of hybrid orbital

1. 2. 3.

one s + one p one s + two p one s + three p

2; sp 2 3; sp 3 4; sp

4.

one s + three p + one d

5; sp d

5.

one s + three p + two d

6; sp d

6.

one s + three p + three d

7; sp d

3D orientation Linear Triangular Tetrahedral

Example BeH2, BeCl2 BCl3, BF3 CH4, CCl4

3

Triangular bipyramidal

PCl5

3 2

Octahedral /Square bipyramidal

SF6

Pentagonal bipyramidal

IF7

3 3

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

No. of hybrid orbitals : No. of atomic orbitals participate in intermixing Hybrid orbitals oriented at maximum possible distance three dimensionally. Type of hybridisation.

E

Chemistry HandBook

C HAP TE R

ALLEN

VALENCE SHELL ELECTRON PAIR REPULSION THEORY

o o o

Given by Nyholm & Gillespie to define shape of molecule.

o

Order of replusion :

Shape of molecule define on the basis of electron pairs orientation present on central atom. Electron pairs present on central atom repel each other therefore these electron pair occupy such position on central atom; where they experience minimum repulsion at maximum possible distance three dimensionally. lp-lp > lp-bp > bp-bp

mb-mb > mb-sb > sb-sb

TYPE OF HYBRIDISATION & POSSIBLE STRUCTURE No. of B.P.

Type of Hybridisation

No. of L.P.

Shape

1. sp-hybridisation

2

-

Linear

BeF2, CO2, CS 2,BeCl2

2. (a) sp2-hybridisation 2 (b) sp -hybridisation

3 2

1

Trigonal planar V-shape,Angular

BF3, AlCl3, BeF3— — NO2 , SO2, O3

4 3 2

0 1 2

Tetrahedral Pyramidal V-shape Angular

CH4, CCl 4, PCl4 , ClO4 , NH4 , BF 4 , SO4 , AlCl4 NH3, PF 3, ClO3—, H 3O +, PCl 3, XeO3,N(CH 3) 3, CH 3— H2O, H2S, NH2— + OF2, Cl2O, SF2, I3

4. (a)sp d-hybridisation (b) sp3d-hybridisation

5 4

1

(c) sp3d-hybridisation (d) sp 3d-hybridisation

3 2

2 3

Trigonal bipyramidal See-Saw, folded square distorted tetrahedral almost T-shape Linear

PCl5, SOF 4, AsF 5 SF4, PF4—, AsF4— SbF4—, XeO2F2 ClF3, ICl3 I3—, Br3—, ICl2—, ClF 2—, XeF2

5. (a) sp3d2-hybridisation (b) sp3d2-hybridisation 3 2 (c) sp d -hybridisation

6 5 4

1 2

Square bipyramidal/octahedral Square pyramidal/distorted octahedral Square planar

PCl 6—, SF 6 XeOF 4, ClF5, SF5—, XeF5+ XeF 4

6. (a) sp d -hybridisation (b) sp3d3-hybridisation

7 6

1

(c) sp3d3-hybridisation

5

2

Pentagonal bipyramidal IF 7 Pentagonal pyramidal/ XeF 6 distorted octahedral /capped octahedral Pentagonal planar XeF 5—

3

3. (a) sp -hybridisation (b) sp3-hybridisation (c) sp3-hybridisation 3

3 3

DIPOLE MOMENT Measurement of Polarity in a molecule m = q ×d

debye = esu-cm 1D = 10—18 esu.cm

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

(A) Identification of polar or Non-polar molecule. Molecule : Symmetrical distribution of electron cloud- Non-polar. Molecule : Unsymmetrical distribution of electron cloud- Polar.

E

Examples

Diatomic Molecule (a) Homoatomic D EN = 0 ® m = 0 ® Non-polar H2, F 2, Cl2, N2 etc. (b) Heteroatomic D EN ¹ 0 ® m net= 0 ® polar HF > HCl > HBr > HI Polyatomic molecule : m R ® Vector sum of bond moment m R ® m 12+m 22+2m 1m 2 cosq Important Order NH3 > NI3 > NBr3 > NCl3 > NF3 NH3>SbH3>AsH3 > PH3 H2O > H2S CH3Cl > CH3F > CH3Br > CH3I CH3Cl > CH2Cl2 > CHCl3 > CCl 4

+

—

+

-1

-2

—

Applications Predict shape and polarity of molecule Symmetrical geometry ® m =0 ® non-polar Unsymmetrical geometry ® m ¹ 0 ® polar Distinguish between cis & trans form H H

C

CH3

C CH3

H

C

CH3

CH3 C H

maleic acid m¹ 0

fumaric acid m= 0

Dipole moment in Aromatic Compounds Cl

Cl

Cl

Cl Cl Cl Orthodichloro benzene

metadichloro benzene

mµ

paradichloro benzene

1 bond angle

63

Chemistry HandBook

CHAPTER

ALLEN

HYDROGEN BONDING Electrostatic force of attraction between hydrogen & highly electronegative atoms. It is dipole-dipole type of attraction Hydrogen should be covalently bonded with highly electronegative elements. Like : F,O & N. Strength of H-bond µ Electronegativity of electronegative elements Strength Intermolecular H-bond > Intramolecular H-bond Intramolecular H-bonding takes place in ortho derivatives only.

Type of Hydrogen Bond Intermolecular

Intramolecular

E X AM P L ES

Between molecule

Applications of H-bonding Physical State (densile nature) µ H-bond Melting Point (mp) µ H-bond Boiling Point (bp) µ H-bond Viscosity µ H-bond Surface Tension µ H-bond Volatility µ 1/H-bond Vapour Pressure µ 1/H-bond

Within molecule It is not an intermolecular force

H2O is liquid while H2S is gas. HF is liquid while HCl is gas. Viscosity & Surface Tension

CH 2—OH CH—OH > CH2 OH

CH2—OH CH 2—OH

>CH 3—OH

Specific

Solubility in H2O : Any organic compound which get dissolve in H2O, it is due to H-bonding.

Examples

Association of Molecule : KHF2 is possible but not KHCl2 it is due to K [F -----H—F]

+

—

ion dipole type h-bond

MOLECULAR ORBITAL THEORY Given by Hund & Mulliken given Given To explain : O2 : Paramagnetic nature. Existence of species like H2+, H2—

As per MOT bond form by combination of atomic orbitals & interference of electron wave interference of electron wave leads to formation of molecular orbitals.

atomic orbitals - electron waves - interference Constructive Interference same phase wave - bonding molecular orbital (BMO)

constructive interference destructive interference

Destructive Interference opposite phase wave - anti-bonding molecular orbital (ABMO)

All atomic orbitals of an atom participate in combination and form molecular orbitals with atomic orbitals of another atom. Energy level of molecular orbital s1s s*1s s2s s*2s p2px= p2py s2pz p*2px = p*2py s*2p z Total electron SrCl2>BaCl2

cation size ­ polarisation¯ covalent character¯

Covalent character ­

(ii) SF2 < SF4 < SF6 -1

(2) Polarisation µ

-3

Covalent character ­ (anion charge­)

(iii) LiF < Li2O < Li3N

SOLUBILITY For s-block same group cation Lattice Energy /Hydration Energy IA

(i) If common ion smaller 1 µ size solubility µ LE

IIA (ii) If common ion larger

IA

—2

—

—

—2

—

—

For all

—2

O , OH , F , SO4 , CO O , OH , F

—2 3

Eg. (i) PbF2 > PbCl2 > PbCl2 > PbI2 (Anion size­, cov. char.­, solubility ¯)

—

—

— 4

Br , I , ClO

(ii) Fe+2(OH)2 > Fe+3(OH)3 (+) charge­, PP­, CC ­, solubility ¯

CO —2, SO4—2, NO3—, Br—, IIA — 3 —2 —2 — I , S , S2O3 , Cl Eg. (i) Li2CO 3 < Na 2CO3 < K2CO3 < Rb2CO3 < Cs2CO 3 common ion smaller (CO3—2) solubilityµ

1 LE

(ii) BeCO3 > MgCO3 > CaCO3 > SrCO3 > BaCO3 common ion larger (CO

) solubility µ HE

—2 3

(iii) BeSO4 > MgSO4 > CaSO4 > SrSO4 > BaSO4 common ion SO4—2 larger solubility µ HE

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

1 cov. char.

1 ionic char [CCl4, benzene, ether, alcohol, acetone]

solubility µ HE

E

solubility µ

(iii) ZnCl2 > CdCl2 > HgCl2 Zeff­, PP­, CC ­, solubility ¯ (iv) Na2SO4 > MgSO4 (+)charge­, PP­, CC ­, solubility ¯ (v) ZnCl2 > CdCl2 > HgCl2 Zeff­, PP­, CC ­, solubility ¯ (vi) NaCl > CuCl PP­, CC ­, solubility ¯ (vii) AgF > AgCl > AgBr > AgI Anionic Size­, PP ­, CC­, solubility ¯

IMPORTANT NOTES

67

Chemistry HandBook

CHAPTER

ALLEN

THERMAL STABILITY/THERMAL DECOMPOSITION For Momoatomic Anions

For Polyatomic Anions

(X–, H–, O–2, etc.)

–2

(CO3 , HCO3–1, SO4–2, OH –1, O2–2, O2–1 etc.)

In a gp : T.S. µ L.E. µ 1 Size

T.S. µ

1 µ size of cation Polarisation

In a Pd : T.S. µ D EN eg. : 1. LiF > NaF > KF > RbF > CsF

eg. : 1. Li2CO3 < Na 2CO3 NaH > KH > RbH > CsH

2. BeSO4 < MgSO4

Inter

More mass

Intra

>

Vanderwaal

Less mass • If mass is same MP µ Polarity of molecule

>

H-Bond

Molecular solid

C HAP TE R

MP & BP µ

MP µ

MP µ L.E.

IIA

Large anion

Ionic solid

M.P. and B.P. (General order)

With small anion

MP µ L.E.

IA

For p & d - block metal compound

Covalent solid B4C, SiC, Diamond, Graphite etc.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

ALLEN Chemistry HandBook

69

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Chemistry HandBook

70 ALLEN

IMPORTANT NOTES

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

71

Chemistry HandBook

CHAPTER

ALLEN

s-BLOCK ELEMENTS Chemical property of alkali metal & alkaline earth metal

i

Order of metallic or Ionic radii%

i

Reaction with air (N2 & O2) All forms their normal oxide & nitrides. Exception : Nitride of Na, K, Rb, Cs is not possible.

i

Reaction with O2 & Excess of air Li – normal oxide Be – normal oxide Na – peroxide Mg – normal oxide K – super oxide Ca – peroxide Rb – super oxide Sr – peroxide Cs – super oxide Ba – peroxide

i

Reaction with H 2 O : All form their hydroxide & H2 gas Order of basic strength : Cs2O > Rb2O > K2O > Na2O > Li2O BaO > SrO > CaO > MgO > BeO CsOH > RbOH > KOH > NaOH > LiOH Ba(OH)2>Sr(OH2)>Ca(OH)2>Mg(OH)2> Be(OH)2 Exception : Be does not react with H2O , Mg reacts with hot water. Order of reactivity with H2O in IA and IIA group Cs > Rb > K > Na > Li Ba > Sr > Ca > Mg > Be

i

CO3–2 & SO4–2 salt of Na, K, Rb and Cs only are not decomposed on heating due to large size and weak polarising power.

i

In nitrate salts

Cs > Rb > K > Ba > Sr > Ca > Na > Mg > Li > Be i

i

Order of density : Ist A

Cs > Rb > Na > K > Li

IInd A

Ba > Sr > Be > Mg > Ca

Order of MP & BP% Ist A

Li > Na > K > Rb > Cs

II A

Be > Ca > Sr > Ba > Mg

nd

i

i

i

i

Order of hydration in cation : IA

Li+ > Na+ > K+ > Rb+ > Cs+

IIA

Be+2 > Mg+2 > Ca+2 > Sr+2 > Ba+2

Order of conductivity of cations in polar solvent IA

Cs+ > Rb+ > K+ > Na+ > Li+

IIA

Ba+2 > Sr+2 > Ca+2 > Mg+2 > Be+2

Order of conductivity in non-polar solvent IA

Li+ > Na+ > K+ > Rb+ > Cs+

IIA

Be+2 > Mg+2 > Ca+2 > Sr+2 > Ba +2

Colour of s-block metal in flame test Li

Crimson red

Na

Golden yellow

K

Pale violet

Rb

D ® Na/K/Rb/CsNO2 + 2Na/K/Rb/CsNO3 ¾¾¾¾ 800° C >

Reddish violet

Cs

Sky blue

D

® Na/K/Rb/Cs O+N + 800° C or 2Na/K/Rb/CsNO3¾¾¾¾ 2 2 800° C
H2S > H2Se > H2Te Bond angle : 104.5° 92.5° 91° 90° (all sp3 hybridised)

l

SO3 is a gas, sp2 hybridised and planar in nature. O é1pp - pp ù S ê ú ë 2 pp - d p û O O O O O

S l

S

S

O O O O O O In solid state it exists as a cyclic trimer (SO3)3, a-form or as linear cross-linked sheets, b-form. O O sp3 S sp3 S = O bond Þ 6 O O S - O - S bond Þ 3 O S S O O O O a-form

85

Chemistry HandBook

CHAPTER

ALLEN

OXYGEN (O2)

OZONE (O3)

p Preparation : By action of heat on oxygen rich compounds : l From oxides : D 2Hg O ¾¾® 2Hg + O2 l From peroxides : 2Na2O2 + 2H2O ¾® O2 + 4NaOH D 2BaO2 ¾¾® 2BaO + O2 l From decomposition of certain compounds D 2KClO3 ¾¾¾® 2KCl + 3O2 MnO2

2KNO3 ¾® 2KNO2 + 3O2 p Chemical properties : On heating it combines directly with metals and non-metals, causing oxidation. C + O2 ¾® CO2 S + O2 ¾® SO2 Pb + O2 ¾® PbO2 2CH3OH + O2 ¾® 2HCHO + 2H2O p Uses % l When mixed with He or CO2, it is used for artificial respiration. l In welding and cutting. l As a fuel in rockets.

p Preparation : l Lab method : ˆˆˆˆˆˆˆˆ† ˆ 3O2 ‡ˆˆˆˆˆˆˆˆ ˆ 2O3 (DH = +ve) Electric discharge

p Properties : Pale blue gas with characteristic strong smell, slightly soluble in water but more soluble in turpentine oil or glacial acetic acid. l Decomposition: 573K 2O3 ¾¾¾ ® 3O2 + 68kcal

l Oxidising action: O3 ¾® O2 + O PbS + 4O ¾® PbSO4 l Reducing action: H2O2 + O3 ¾® H2O +2O2 BaO2 + O3 ¾® BaO + 2O2 p Ozone reaction: (i) Tailing of Mercury : 2Hg + O2 ¾® Hg2O + O2 (ii) Estimation of Ozone : 2KI + H2O + O3 ¾® O2 + I2 + KOH (Na2 S2O3 .5H2O) ® 2NaI + Na2S 4O6 I2 ¾¾¾¾¾¾

p Uses : l Bleaching ivory, flower, delicate fabrics, etc. l As germicide and disinfectant, for sterilising water. l Manufacture of KMnO4 and artificial silk.

SULPHUR DIOXIDE (SO2) p

Preparation %

p

D By heating sulphur in air. S + O2 ¾¾ ® SO2 l Lab method : By heating Cu with conc. H2SO4. Cu + 2H2SO4 ¾® CuSO4 + SO2 + 2H2O Properties : l As reducing agent % SO2 + Cl2 + 2H2O ¾® H2SO4 + 2HCl 2KMnO4 + 5SO2 + 2H2O ¾® K2SO4 + 2MnSO4 + 2H2SO4 l As oxidising agent : 2H2S + SO2 ¾® 2H2O + 3S¯ l Bleaching action : Its bleaching action is due to reduction. SO2 + 2H2O ¾® H2SO4 + 2H Coloured matter + H ¾® Colourless matter.

2(Nascent hydrogen)

p

86

Uses : l In the manufacture of sulphuric acid,sulphites and hydrogen sulphide. l As a disinfectant and fumigate. l For bleaching delicate articles.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

l

E

Chemistry HandBook

C HAP TE R

ALLEN

SULPHURIC ACID (H2SO4)

It is also known as oil of vitriol and king of chemicals. p Manufacture of sulphuric acid : l Lead chamber process : The various steps involved are : l Contact process : Step involved (a) Production of SO2

GROUP 17 ELEMENTS p Reactivity : All halogens are chemically very reactive elements. This is due to their low dissociation energy and high EN. Fluorine is the most reactive and iodine is the least reactive halogen. p Oxidising power : F is the most oxidising element due to high hydration enthalpy. F2 > Cl2 > Br2 > I2.

S + O2 ¾® SO2 M.Sulphide + O2 ¾® SO2 (b) Conversion of SO2 to SO3 ˆˆˆˆ† ˆ SO2 O2 ‡ˆˆˆˆ ˆ SO3 V2O5

(c) SO3 + H2SO4 ¾® H2S2O7 oleum H2S2O7 +H2O ¾® 2H2SO4 p Properties : Its specific gravity is 1.8 and it is 98% by weight.

HYDROGEN HALIDES Bond strength, bond length and thermal stability : • Since size of halogen atom increases from F to I down the group, bond length of H – X bond increases down the group. \ reactivity and acidic character ­. HF < HCl < HBr < HI. • Bond strength order HF > HCl > HBr > HI. • Bond energy order

l It is strong dibasic acid. H2SO4 ƒ 2H+ + SO42– l It acts as an oxidising agent. H2SO4 ¾® H2O + SO2 + O

HF > HCl > HBr > HI. REDUCING CHARACTER : The reducing character of hydrogen halides increases down the group as HF < HCl < HBr < HI.

l Non metals are oxidised to their oxides and metals to the corresponding sulphates. C + 2O ¾® CO2

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

l Dehydrating agent : It is strongly dehydrating in nature.

E

H2 SO 4 C12H22O11 ¾¾¾¾ ® 12C + 11H2O

(Charring of sugar) p Uses : l In lead storage batteries. l In manufacture of paints and pigments. l In metallurgy for electrolytic refining of metals.

2HX ¾® H2 + X2 A less thermally stable compound has more tendency to release hydrogen easily and show greater reducing property. OXIDES : F ¾® O2F2, OF2 Cl ¾® Cl2O, Cl2O3, Cl2O5, Cl2O7, Cl2O2, ClO3 Br ¾® Br2O, Br2O7, Br2O5 I ¾® I2O, I2O7, I2O5, I4O9 (Ionic) Stability : I > Cl > Br (Middle row anormaly)

87

CHAPTER

CHLORINE (Cl2) p Preparation : By oxidation of conc. HCl. PbO2 + 4HCl ¾® PbCl2 + 2H2O + Cl2 2KMnO4+16HCl ® 2KCl+2MnCl2+8H2O+5Cl2 p Manufacture : Weldon's process : By heating pyrolusite with conc. HCl. MnO2 + 4HCl ¾® MnCl2 + 2H2O + Cl2 p Properties : It is a yellowish green gas, poisonous in nature, soluble in water. Its aqueous solution is known as chlorine water which on careful cooling gives chlorine hydrate Cl2.8H2O. Bleaching action and oxidising property (i) Cl2 + H2O ¾® HOCl + HCl HOCl ¾® HCl + [O] Coloured matter + nascent [O] ® Colourless matter The bleaching action of chlorine is permanent and is due to its oxidising nature. (ii) SO2 + Cl2 + 2H2O ¾® H2SO4 + 2HCl Oxidising behaviour of Cl2 Cl2 Fe+2

Fe+3

–2

SO4

I2

HIO3

Br–/I–

Br2/I2

SO3

–2

Cl– l Addition reactions : SO2 + Cl2 ¾® SO2Cl2 CO + Cl2 ¾® COCl2 p USES : l It is used as a (i) bleaching agent (ii) disinfectant (iii) in the manufacture of CHCl3, CCl4, DDT, bleaching powder, poisonous gas phosgene (COCl2), tear gas (CCl3NO2) and mustard gas (ClC2H4SC2H4Cl).

88

ALLEN

HYDROCHLORIC ACID, (HCl) p Preparation : By dissolving hydrogen chloride gas in water. Hydrogen chloride gas required in turn can be prepared by the following methods: l By the direct combination of hydrogen and chlorine. Sunlight H2(g) + Cl2(g) ¾¾¾¾ ® 2HCl(g)

l Hydrogen chloride gas can also be obtained by burning hydrogen in chlorine. l By heating halid with conc. H2SO4 NaCl + H2SO4 ¾® NaHSO4 + HCl NaHSO4 + NaCl ¾® Na2SO4 + HCl Imp. Points : l HCl cannot be dried by P2O5 or quick lime. CaO + 2HCl ¾® CaCl2 + H2 P4O10 + 3HCl ¾® POCl3 + 3HPO3 l Reducing property : HCl is a strong reducing agent. MnO2 + 4HCl ¾® MnCl2 + 2H2O + Cl2 p Uses : l In the production of dyes, paints, photographic chemicals, etc. l Used in the preparation of chlorides, chlorine, aquaregia, etc. l Used as a laboratory reagent.

INTERHALOGEN COMPOUNDS p These compounds are regarded as halides of more electropositive (i.e. less elecronegative) halogens. p Types of interhalogen compound : AB type : ClF, BrF, BrCl, ICl, IBr AB3 type : ClF3, BrF3, ICl3 AB5 type : BrF5, IF5 AB7 type : IF7 USES OF INERT GASES : (1) He is non-inflammable and light gas, so it is used in filling balloons for meteorological observations. (2) He is used in gas cooled nuclear reactors. (3) Liquid He is used as cryogenic agent. (4) He is used to produce powerful superconducting magnets. (5) Ne is used in discharge tubes. (6) Ar is used as inert atmosphere in metallurgical process. (7) Xenon and Krypton are used in light bulbs designed for special purposes. (8) He is used as a diluent for oxygen in modern diving apparatus due to its very low solubility in blood.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Chemistry HandBook

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

89

Chemistry HandBook

CHAPTER

ALLEN

COORDINATION CHEMISTRY Complex Compound Representation of coordination compound K4 [Fe(CN)6]

C.N.

(coordination no.)

Ionisation sphere / Counter Ion Coordination sphere / Entity Central metal atom/ion Ligand

LIGANDS Species which donate lone pair/ electron pair is called as ligand, on the basis of the number of e pairs available for donation; ligands are classified as LIGANDS On the basis of denticity

On the basis of charge Neutral Anionic Cationic

Monodentate Bidentate Polydentate Flexidentate Ambidentate

Classical

Non-classical

p e— donating ligand

— Eg. CH2=CH2, COO | COO—

These are the polydentate ligands LIGAND

AMBIDENTATE

which bind to the central metal to form a puckered ring structure. Chelation leads to extra stability, for example, EDTA (ethylene diamine tetra acetate).

FLEXIDENTATE LIGANDS

Exhibit variable denticity.

2—

2—

Eg. SO4 , CO3 , EDTA

4—

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Bidentate : Contain two donor sites.

They can change their donor atom (side) but not denticity. Eg. : — — — –CN , and –NC , –SCN — — — and –NCS , NO2 and ONO , — — –OCN and NCO . These ligands are responsible for linkage isomerism.

90

p acid ligand

Monodentate : have only one donor sites. Eg. H2O, NH3

LIGAND

of denticity

lp donation/accepting e—s

CHELATING

On the basis

On the basis of

E

Chemistry HandBook

CH APTER

ALLEN

BONDING

IN

C OORDINATION C HEMISTRY BONDING

Werner Theory

Valence Bond Theory

Crystal Field Theory

WERNER'S THEORY Metal in a complex shows two type of valences - Primary & secondary. Primary valency It is oxidation no. of metal. It is variable Satisfied by anions (present in coordination or ionisable sphere). Ionisable Ionic \ nondirectional Represented by dotted line in Werner structure.

COCl3.4NH3

Eg.

Molecular formula

[Co(NH3)4Cl2]Cl

H 3N

Secondary Valency It is coordination number It is non variable. Satisfied by ligands (present in coordination sphere) Non ionisable Directional \ decide geometry of complex ion. Represented by solid lines in Werner structure.

NH3 Cl Co

complex formula

H3N

Cl

3 dotted line shows - Primary Valence 6 solid line shows - Secondary Valence

NH3 Cl

Werner structure

VALENCE BOND THEORY Central metal atom /ion & ligand come close to each other ligand donate lone pair & CMA provide vacant orbital. There is hybridisation of atomic orbitals provided by central atom to ligands. Type of Orbitals participating in intermixing depend upon two factors. (a) Availability of orbitals (b) Nature of ligand Coorination No. 2 3

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

4

E

5 6

Type of hybrid orbital sp 2 sp 2 square planar -dsp 3 tetrahedral -sp 3 dsp sp3d 3 2 sp d - outer orbital complex (high spin) 2 3 d sp - inner orbital complex (low spin)

Eg. : 2— 3 [NiCl4] sp -----Tetrahedral 2— 2 [Ni(CN)4] dsp ----- Square planar 3 [Ni(CO)4] sp -----Tetrahedral 2+ 3 [Zn(NH3)4] sp -----Tetrahedral 2+ 2 [Cu(NH3) 4] dsp -----Square planar Coordination No. 6 : Example d2sp3 [Fe(CN)6]4— 2 3 3— d sp [Fe(CN)6] 3+ 2 3 d sp [Co(NH3)6] 2+ 3 2 [Ni(H2O)6] sp d

VALENCE BOND THEORY m m

2

3

If the complex is formed by the use of inner d-orbitals for hybridisation (d sp ), it is called inner orbital complex. 3 2 If the complex is formed by the use of outer d-orbitals for hybridisation (sp d ), it is called an outer orbital 3— complex. Such a complex is also called as high spin complex e.g. [CoF6] .

91

Chemistry HandBook

CH AP TE R

ALLEN

CRYSTAL FIELD T HEORY (CFT) CRYSTAL FIELD SPLITTING m

The splitting of five degenerate d-orbitals of the metal into different sets of

m

orbitals having different energies in the presence of electrostatic field of 2 2 2 ligands is called crystal field splitting. egset – dx –y , dz t2g set– dxy, dyz, dxz Crystal field splitting energy, (DO for octahedral structure and Dt =4/9D0 tetrahedral structure) is the difference between the various sets of energy

m

levels formed by crystal field splitting. Weak field ligands are those ligands which cause a small degree of crystal field —

m

—

—

—

—

ISOMERISM

Hydrate

2—

splitting e.g. I , Br , Cl , F , OH , C2O4 , H2O, etc. Strong field ligands are those ligands which cause a high degree of splitting e.g. CO, CN , NO , etc. Spectrochemical series — — — — — — 2— I < Br < Cl < NO3 < F < OH < ox < H2O < py ~ en < dipy < o-phen < –

—

m m m

—

Geometrical

Optical

Linkage Coordination

–

2

m

Stereo

Structural Ionisation

—

NO2 < CN < CO. ( C and N donar act as SFL except N3 ) For 4d & 5d element all ligands acts as S.F.L. +3 –2 With CO (OX) , H2O acts as S.F.L. +2 +2 With Fe & Mn , NH3 act as W.F.L.

Important Point : Extent of synergic bonding

M–C B.L.

C–O B.L.

[M(CO)n]

–

Max.

Min.

Max.

[M(CO)n]

+

Min.

Max.

Min.

Ionisation isomerism : Same molecular formula (b) but gives different ionisable species. (Only anionic)

Hydrate isomerism : Same molecular formula but different number of water molecules associated with central metal. (a) [Cr(H2O)6 ]Cl3

(a) [Pt(NH4)4 Cl2]Br2 PtCl2Br2.4NH3

CrCl3.6H2O (b) [Pt(NH3)4 Br2]Cl2

(c)

Linkage isomerism : Structural isomerism shown by (d) ambidentable ligands

(NO ,CSN ,CN ,CNO etc ) – 2

[Fe(NH3) 5(SCN)]

92

–

2+

–

–

[Fe(NH3)5(NCS)]2+

(b) [Cr(H2O)5Cl]Cl2.H2O (c) [Cr(H2O)4Cl2]Cl.2H2O

Coordination isomerism : Isomers having both anion and cation as complex entity. Can inter change position of ligands as well as metal. [Cr(NH3)6][Co(CN)6]

[Co(NH3)6][Cr(CN)6]

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

STRUCTURAL (a)

E

Chemistry HandBook

CHAP TER

ALLEN

STEREOISOMERISM Sq. planar complex with symmetrical bidentate ligand. Eg. No GI Sq. planar complex can exhibit GI only in two types

M(AB)2 M(AB)(CD)

* On increasing number of one type of ligand total number of geometrical isomers decreases. Whenever same type of ligand placed at 180° it will not show O.I.

[M(AA)2a2] type of complex have two GI (cis & trans) * [M(AA)2a2] type of complex gives three stereo isomer : (1) cis (2) trans (3) mirror image of cis

O RGANOMETALLIC COMPOUDS Compounds in which the less E.N. (Ge, Sb, B, Si, P, As) central metal atoms are bonded directly to carbon atoms are called organometallic compounds. m s - bo nd ed c om p ound s nontransition elements.

fo r m ed

IUPAC nomenclature of complex compounds : (A)

by

Common name of normal cation (without numeral prefix) + name of ligands (with numeral prefix) + latin name of CMI along with suffix ate + Ox. St (in roman number).

R–Mg–X, (CH3–CH2)2Zn, Ziegler natta catalyst, etc.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

m p -bonded organometallic compounds are generally formed by transition elements e.g. Zeise's salt, ferrocene, dibenzene chromium, etc.

E

m s - a n d p - b o n d ed o r g a n o m e t a l li c compounds : Metal carbonyls, compounds formed between metal and carbon monoxide belong to this class. Ni(CO)4, Fe(CO)5etc.

eg. : (B)

For cationic comlex like [Cu(NH3)4]SO4

eg. : (C)

Tetraammine copper (II) sulphate.

For neutral complex (like [Fe(CO)5) Name of ligands (with numeral prefix) + Common name of CMI + Ox. St.

p s

Potassium hexacyanoferrate (II)

Name of ligands (with numeral prefix) + Common name of CMI + Ox. St (In roman number) + Name of anion (without numeral prefix)

Synergic bonding

M

For anionic complex (like K4[Fe(CN)6])

(In roman number)

ABMO C

O

eg. : (D)

Pentacarbonyl iron (O)

Rule same just apply alphabetical order when write the name of ligands. e.g. [Pt(NH3)2Cl2] Diamminedichloroplatinum (II)

93

Chemistry HandBook

C HAP TE R

ALLEN

d-BLOCK (Transition Elements) DEFINITION Incomplete n and n–1 shell in atomic or in ionic state. Zn, Cd & Hg – are d-block nontransition elements.

ns

0–2

(n–1)d

1–10

1 2nd 3rd 4th st

ì Cr = 4s1 3d 5 0 10 Exceptions í 1 10 , Pd = 5s 4d îCu = 4s 3d

TRANSITION SERIES Sc21 — Zn30 Y39 — Cd48 La57, Hf72 — Hg80 Ac89, Unq 104— Uub112

3d series 4d series 5d series 6d series

9 + 1 = 10 9 + 1 = 10 9 + 1 = 10 9 + 1 = 10

ATOMIC RADIUS

OXIDATION STATE

3d series Sc > Ti > V> Cr >Mn ³ Fe ; CO ; Ni £ Cu < Zn

Transition elements exhibit variable oxidation state due to small energy difference of ns and (n–1)d electrons. r Sc(+3) and Zn(+2) exhibit only one oxidation state r Common oxidation state is +2 r 3d series highest oxidation state is +7 (Mn) r In d-block series highest oxidation state is +8 (Os, Ru) r In carbonyl compound oxidation state of metals is zero due to synergic effects. r Their higher oxidation states are more stable in fluoride and oxides. r Higher oxidation states in oxides are normally more stable than fluorides due to capability of oxygen to form multiple bonds. eg. stable fluoride in higher oxidation state of Mn is MnF4 while oxide is Mn2O7 Some more stable oxidation states of d-block elements

In a group 3d to 4d series increases but 4d and 5d series nearly same due to poor shielding of f electron. (Lanthanide contraction) 3d < 4d ; 5d Smallest radius – Ni e.g.% Ti < Zr ; Hf Largest radius – La

Melting point :s-block metals < d-block metals In a series on increasing number of unpaired e– mpt increases upto Cr then decreases. Sc < Ti < V < Cr > Mn < Fe > Co > Ni > Cu > Zn ¯

¯

Half filled d 5 \ weak metallic bond

Melting point

Fully filled d10 \ weak metallic bond

Zn > Cd > Hg Cu > Ag £ Au

(data based)

E.N. Exception Zn < Cd < Hg Density : s-block metals < d-block metals. 3d series Sc < Ti < V < Cr < Mn < Fe < Co £ Ni < Cu > Zn Density in a Group 3d < 4d Cu > Au > Al E5555555555 F p - block d - block

94

Cu +2

Mn +2

Pt +4

Ag +1

Cr +3

Sc +3

Au +3

Ni +2

Common oxidation states Ti(+4),

V(+5)

Fe(+2, +3), Co(+2,+3)

Cr(+3,+6) Mn(+2,+4,+7) Ni (+2)

Pt (+2+4)

In p-block lower oxidation states of heavier elements are more stable while in d-block heavier element, higher oxidation state are more stable. eg. In VIB gp Mo(+6) & W(+6) are more stable than Cr(+6)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

GENERAL ELECTRONIC CONFIGURATION

E

Chemistry HandBook

C HAP TE R

ALLEN

MAGNETIC PROPERTY All transition elements are paramagnetic due to presence of unpaired electrons. They attract when magnetic field is applied. Magnetic moment of unpaired electron is due to spin and orbital angular momentum. "Spin only" magnetic moment can be calculated by using formula m = n(n + 2) Bohr magneton. (n is number of unpaired e–.) If

n is 1 m = 1.73 BM

n is 2 m = 2.84 BM

n is 4 m = 4.90 BM

n is 5 m = 5.92 BM

n is 3 m = 3.87 BM

Substances that are not attracted by applied magnetic field are diamagnetic. They have all the electrons paired. dblock element and ions having d0 and d10 configuration are diamagnetic.

COLOUR Colour in transition metal ions is associated with d–d transition of unpaired electron from t 2g to eg set of energies. This is achieved by absorption of light in the visible spectrum, rest of the light is no longer white. Colourless – Sc3+, Ti4+, Zn2+ etc Coloured – Fe3+ yellow , Fe2+ green, Cu2+ blue, Co3+ blue etc Interstitial compounds : When less reactive nonmetals of small atomic size eg. H, B, N, C, Trapped in the interstitial space of transition metals, interstitial compounds are formed, like :- TiC, Mn4N, Fe3H etc. They are nonstoichiometric compounds.

They have high melting point than metals.

ALLOYS

CATALYST

Solid mixture of metals in a definate ratio

Transition metals & their compounds act as catalyst due to –

(15% difference in metallic radius) They are hard and having high melting point. eg.

They are chemically inert.

Brass (Cu + Zn)

–

Variable oxidation state

–

Tendency to form complex

eg.

Bronze (Cu + Sn) etc. Hg when mix with other metals form semisolid amalgam except Fe,Co,Ni, Li.

V2O5 – Contact process Fe

– Haber process

Ni

– Catalytic hydrogenation

Important reactions of d-block elements

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

(a) Cu2+ + 4I– ¾® Cu2I2(s) + I2

E

2 (b) CuSO4 + KCN ¾® K2SO4 + Cu(CN) Excess Unstable

(e)

100° C 230° C ¾ ® CuSO4 .H2O ¾¾¾ ¾ ® CuSO 4 CuSO 4 .5H 2 O ¾¾¾ light greenish blue

(CN)2 2Cu(CN)2 ¾® 2CuCN + Cyanogen

720° C ¾¾¾ ¾ ® CuO + SO2 +

CuCN + 3KCN ¾® K3[Cu(CN)4] (c)

H2 O + CO2 ® CuCO3 .Cu(OH)2 Cu ¾¾¾¾¾ moist air

(d)

(f)

green

Aqua regia Au ¾¾¾¾¾¾ ® H[AuCl 4 ] + NOCl + H 2 O (3HCl + HNO3 )

Heating AgNO 3 ¾¾¾¾ ® Ag + NO2 +

1 O2 2

Heating AgCO3 ¾¾¾¾ ® Ag + CO2 +

1 O2 2

Colourless

Hg2Cl2 + NH4OH ¾® Hg

1 O2 2

NH2 Cl Black

(g)

FeSO4 + H2 SO4 NO3- / NO2- ¾¾¾¾¾¾ ® éëFe ( H2 O )5 NO + ùû SO 4

Brown ring complex

(h) AgBr + 2Na2S2O3 ¾® Na3[Ag(S2O3)2] + NaBr Photographic complex

95

Chemistry HandBook

C HAP TE R

ALLEN

COMPOUNDS OF D-BLOCK ELEMENT A.

K2Cr2O7 : Method of preparation : 4FeO.Cr2O3 + 8Na2CO3 + 7O2 (Chromite)

8Na2CrO4 + 2Fe2O3 + 8CO2 K2Cr2O7

Important point : •

ˆˆˆˆ † Cr2 O7-2 CrO4-2 ‡ˆˆˆ - ˆ

•

K 2Cr2O7 used in volumetric analysis not Na2Cr2O7.

•

D ® 2K 2CrO 4 + Cr2O3 + O2 Hetaing effect ® 2K 2Cr2 O7 ¾¾

•

Chromyl chloride test ® Used to detect ionic chloride (Cl–)

H+

Yellow

OH

Orange

3 2

NaCl + K2Cr2O7 + H2SO4 ¾® CrO2Cl2 (Red orange) •

With H2O2 ® Cr2O7–2 + H+ + 4H2O2 ¾® CrO5 (Deep Blue sol.)

•

Act as an oxidising agent.

H2S

S

SO2

SO4–2

–

NO3–

SO3–2

SO4–2

Sn+2

Sn+4

Fe+2

Fe+3

Br–

Br2

NO2

I

–

I2

C2H5OH

CH3COOH (drunken drive test) +3

Cr (green)

96

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Acidified K2Cr2O7 (Orange)

E

B.

Chemistry HandBook

C HAP TE R

ALLEN

KMnO4 : Method of preparation : Cl2 KOH MnO2

K2CO3

K2MnO4

H2O + O3

K2MnO4 (Green)

CO2

KMnO4 KMnO4 KMnO4 (Purple)

Property : •

Effect of heating : 2KMnO4 ¾® K2MnO4 + MnO2 + O2

•

With conc. H2SO4 : conc. ® Mn2 O7 (explosive) KMnO 4 ¾¾¾¾ H2 SO 4

•

acts as oxidising agent in Acidic/Neutral/Alkaline (a)

Acidic

(b)

Neutral/Weak alkaline

KMnO4 H2S

S

SO2

SO4

–

NO3

NO2 Fe

+2

Fe

–

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

–2

S2O3

BrO3–

I–

IO3–

–2

SO4

–2

Mn+2

+3

MnO2 MnO4

Cl2

H2CrO4 S2O3

Br–

–

Cl

E

KMnO4

CO2 + H2O

–2

–2

S4O6 +2

Mn

97

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Chemistry HandBook

98 ALLEN

IMPORTANT NOTES

E

Chemistry HandBook

CHAP TER

ALLEN

METALLURGY Branch of process to extract metal from their respective ore Ore : Minerals from which metal can be extracted economically & easily.

METALLURGICAL PROCESS

TYPES OF METALLURGY Pyrometallurgy

Hydrometallurgy

Electro metallurgy

Temp. is involved

Solution is involved

Electric involved

For heavy metals

According to E.C.S.

eg. IA, IIA, Al

eg. Fe, Zn, Cu, Hg, Sn, etc

For metals placed below H

1. Mining : Ore obtain in big lumps (less reactive) 2. Crushing/grinding/pulverization : Big lumps convert into powder (more reactive) 3. Concentration : To remove matrix/ gangue (major impurities) from ore To increase the concenration of ore particle in ore sample.

eg. Cu, Ag, Au

CONCENTRATION (I) Physical process

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

(a) Gravity separation /Hydraulic washing/ Levigation

E

(b) Magnetic separation

(II) Chemical/leaching

for

(c) Froath floatation

Al Ag, Au Baeyer process (NaOH)

Based on diff. in sp. gravity

Based on diff. in mag. properties

Based on diff. in wetting properties

for oxides/ carbonates ore

Used to separate s & p block compound from transitional elements compounds

Sulphide ores

Ag, Au, are concentrated by cyanide process.

Red(Fe2O3) Al2O32H2O

Hall process (Na2CO3)

White(SiO2) Serpeck process (C & N)

Frother - pine oil Floating agent - sodium ethyl xanthate depressant - NaCN

CALCINATION & ROASTING (I) Calcination

(II) Roasting

In absence of air

In presence of air

for Carbonate /Hydroxide/Oxide ore

for Sulphide ore

CO2 & H2O are to be removed

Impurity of S, P, As, SO2 to be removed

MCO3 ® MO + CO2­

MS + O2 ® MO + SO 2­

M(OH)2 ® MO + H2 O­

99

Chemistry HandBook

CHAP TER

ALLEN

REDUCTION : To obtain metal (95 to 98%) from metal oxide.

Extraction of Al(Hall-Herault Process) ! Al can be extracted from Al 2O3 ! To decrease fusion temp. of Al2O3, Na3 AlF6 & CaF2 is to added ! Na3 AlF6 & CaF2 (Neutral flux) increase the conductivity & reduce the fusion temp.

Extraction of Na (Down cell process) ! Na can be extracted from NaCl ! Neutral flux (CaCl2) to be added to decrease the fusion temp of NaCl ! Neutral flux - substance used to increase the conductivity of NaCl ! Decrease the fusion temp. of ionic compounds of (IA, IIA, Al) which is more than the melting point of metal.

l

l l l l

100

The graphical representationof Gibbs energy was first used by H.I.T. Ellingham. This provide a sound basis for considering the choice of reducing agent in the reduction of oxides. This is known as Ellingham diagram such diagram help us in predicting the feasibility of thermal reduction of an ore. The criteria of feasibility is that at a given temperature, Gibbs energy of reaction must be negative. At high temperature 'C' is the best reducing agent. At low temperature 'CO' is the best reducing agent. In blast furnace reduction takes place at low temperature

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

REFINING : To obtain metal (99.98%)

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

101

C HAP TE R

Chemistry HandBook

ALLEN

HYDROGEN Method of preparation : (A) Metal placed about H on reaction with acid. Base or H2O can produce H2. Base + Amp. metal ¾¾® Soluble complex + H2 (Be,Al,Zn,Sn,Pb)

Acid + Metal ¾¾® M.Salt + H2 ( dil )

(B)

Water + Highly reactive metal ¾® M. hydroxide + H2 Important point : • Only Mn, Mg gives H2 on reaction with very dil HNO3. From hydrocarbon : 1270K ® nCO + (3n + 1)H2 Cn H2n +2 + nH2O ¾¾¾¾ Ni

CH 4 + H2 O ¾¾® CO + 3H2 E555555F syn.gas

Ionic hydride – s-block element (except, Be & Mg) (forms polymer having 2e-3c bond) Interstitial hydride – d & f-block element Hydride

– Non stoichiometric compound – Metallic hydride Covalent hydride – p-block element

Electron deficient th (Group 13 ) BH3 Electron precise th (Group 14 ) CH4

Heavy Water (D2O) – Dur to repeated electrolysis of H2O. – Chemical reaction some as H2O but rate of reaction are slow. – N2O5 + H2O ¾® 2HNO3 (Nitric acid) N2O5 + D2O ¾® 2DNO3 (Deutero nitric acid) – Used as a neutron moderation and used in nuclear reactor. H2O2 - Hydrogen peroxide. Method of preparation (a) BaO2.8H2O(s) + H2SO4 ¾® BaSO4 + H2O2(aq) + H2O(l) (b) Electrolytic process - 50% H2SO4 At cathode 2H+ + 2e– ¾® H2 At anode 2HSO4– ¾® H2S2O8 H2S2O8 + 2H2O ¾® 2H2SO4 + H2O2

102

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Electron rich hydride th th th 15 , 16 , 17 group

E

C HAP TE R

Chemistry HandBook

ALLEN

Property : Can acts as oxidising as well as reducing agent. R.A. H2O2

O2

O.A.

H2O

disproportionali

H2O + 1 O2 2

• Non-planar. Half open book like structure. Uses - Bleaching agent, Antiseptic (H2O2 + N2H4) as Rocket propellent, 30% solution of H2O2 is known as perhydrol. Hardness - Due to HCO3 , Cl & SO4 of Ca & Mg –

Temporary hardness – +2 +2 (HCO3 of Ca & Mg )

–

–2

+2

+2

by boiling Ca(HCO3)2 Mg(HCO3)2

D D

CaCO3 + H2O + CO2 Mg(OH)2 + 2CO2

Clarke process - addition of slaked lime Ca(HCO3)2 + Ca(OH)2 2CaCO3 + 2H2O

Hardness

Permanent hardness – –2 +2 +2 (Cl , SO4 of Ca & Mg )

Washing soda (Na2CO3) CaCl2 + Na2CO3 CaCO3¯ + 2NaCl Calgon - Sodium hexametaphosphate Na2[Na4(PO3)6] Permutit - Hydrated sodium alumino silicat

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Na2Al2Si2O8.xH2O (Sodium Zeolite)

E

Ion exchange resin

Cation exchange – RCOO H|+

Anion exchange resis + – R–NH3 OH

103

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\2_INORGANIC.P65

Chemistry HandBook

104 ALLEN

IMPORTANT NOTES

E

ORGANIC CHEMISTRY

CHAPTER

Chemistry HandBook

ALLEN

Carboxylic acid The order of priority of functional groups used in IUPAC nomenclature of organic compounds.

TABLE FOR IUPAC NOMENCLATURE

Sulphonic acid

O –C–OH –SO3H

Anhydride

Ester Acid halide Acid amide Carbonitrile/Cyanide Aldehyde Ketone

O –C–OR O –C–X O –C–NH2 –CºN O –C–H O –C–

Prefix

Carboxy

Suffix

- oic acid *Carboxylic acid

Sulpho

sulphonic acid

×

oic-anhydride

Alkoxy carbonyl or Carbalkoxy

alkyl....oate

Haloformyl or Halocarbonyl Carbamoyl/ Amido Cyano Formyl or Oxo

*Carboxylate

- oyl halide *Carbonyl halide

- amide *Carboxamide

nitrile

*Carbonitrile

- al

*Carbaldehyde

Keto or oxo

- one

Alcohol

–OH

Hydroxy

- ol

Thio alcohol

–SH

Mercapto

thiol

Amine

–NH 2

Amino

amine

Ether

–O–R

Alkoxy

–

Epoxy

–

Nitro

–

Nitro derivative

–C – C– O –NO 2

Nitroso derivative

–NO

Nitroso

–

Halide

–X

Halo

–

Oxirane

Double bond

C=C

–

ene

Triple bond

CºC

–

yne

* Special suffix

106

Structure

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

Functional group

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

107

CHAPTER

Chemistry HandBook

ALLEN

ISOMERISM DEFINITION Compounds having same molecular formula but differ in atleast one physical or chemical or biological properties are called isomers and this phenomena is known as isomerism.

Types of Isomerism : (A) Structural isomerism

(B) Stereo isomerism

(A) STRUCTURAL ISOMERISM Structural isomerism is a form of isomerism in which molecules with the same molecular formula have atoms bonded together in different orders. TYPES OF STRUCTURAL ISOMERISM CHAIN ISOMERISM This type of isomerism is due to difference in the arrangement of carbon atoms constituting the chain. Key points : Parent carbon chain or side chain should be different. e.g. C5H12 : CH3 – CH2 – CH2 – CH2 – CH3

n-propyl methylether

CH3 – CH2 – O – CH2 – CH3

n-pentane

diethyl ether

CH3

RING-CHAIN ISOMERISM In this type of isomerism, one isomer is open chain but another is cyclic.

CH3

CH3

iso-pentane

neo-pentane

POSITIONAL ISOMERISM It occurs when functional groups or multiple bonds or substituents are in different positions on the same carbon chain. Key point : Parent carbon chain remain same and substituent, multiple bond and functional group changes its position. CH3

CH3

e.g. C6H4(CH3)2 :

, o-xylene

CH3

m-xylene

CH3

,

CH3

p-xylene

FUNCTIONAL ISOMERISM It occurs when compounds have the same molecular formula but different functional groups. e.g. C3H9N : CH3– CH2 – CH2 – NH2, 1-propanamine

CH3 – CH2 – NH – CH3, N-methylethanamine

CH3

CH3 – N – CH3, N, N-dimethylmethanamine

108

e.g. C3H6 : CH3 – CH = CH2 propene

CH2 H2C–CH2 cyclopropane

• For chain, positional and metamerism, functional group must be same. • Metamerism may also show chain and position isomerism but priority is given to metamerism. TAUTOMERISM This type of isomerism is due to spontaneous interconversion of two isomeric forms into each other with different functional groups in dynamic equilibrium. Conditions : O O (i) Presence of – C – or – N ® O (ii) Presence of at least one a-H atom which is attached to a saturated C-atom. e.g. Acetoacetic ester. O OH

CH3–C–CH2COOC2H5

CH3–C=CHCOOC2H5

keto form

enol form

ENOL CONTENT ENHANCE BY: * Acidity of a-H of keto form * Intra molecular H-Bonding in enol form * Resonance in enol form * Aromatisation in enol form

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

H3C – CH – CH2 – CH3 , H3C – C – CH 3

CH 3

METAMERISM This type of isomerism occurs when the isomers differ with respect to the nature of alkyl groups around the same polyvalent functional group. e.g. C4H10O : CH3 – O – CH2 – CH2 – CH3

E

CHAPTER

Chemistry HandBook

ALLEN

(B)STEREOISOMERISM Compounds with the same molecular formula and structural formula but having difference in the spatial arrangement of atoms or groups in 3D space are called stereoisomers and the phenomenon is called stereoisomerism. TYPES OF STEREOISOMERISM GEOMETRICAL ISOMERISM

OPTICAL ISOMERISM

It is due to restricted rotation and is observed in following systems

Compounds having same molecular and structural formula but different behaviour towards plane polarised light are called optical isomers and this phenomenon is called optical isomersim.

a

a C=C

b

a

b , b

C=N–OH

, a

e.g.

H HOOC

C CH3

C=C

H

H

COOH

HOOC

cis maleic acid

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

b b

b

C=C

l

The carbon atom linked to four different groups is called chiral carbon.

l

Fischer projection : An optical isomer can be represented by Fischer projection which is planar representation of three dimensional structure. Fischer projection representation of lactic acid

COOH

(2-hydroxypropanoic acid)

H 3

trans > cis

(ii) Dipole moment

cis > trans

(iii) Boiling point

cis > trans

(iv) Melting point

trans > cis

Calculation of number of geometrical isomers : Unsymmetrical

2n

Symmetrical

2n–1 + 2 m–1 n 2

2

COOH

1

C H 3 – C H – C O O H : HO

General physical properties of geometrical isomer of but-2-ene (i) Stability

Optically inactive • meso

Condition :

l

trans fumaric acid

m=

Types of optical isomers (1)Optically active (2) • dextrorotatory (d) • laevorotatory (l)

l

Molecule should be asymmetric or chiral i.e. symmetry element (POS & COS) should be absent.

Cis-trans isomerism : The cis compound is the one with the same groups on the same side of the bond, and the trans has the same groups on the opposite sides. Both isomers have different physical and chemical properties.

l

E

a a

b,

a

(Ring greater than 7 member with , double bond)

l

N=N

n +1 m= (If n is odd) 2

OH

H

OH CH3

l

Configuration of optical isomer : (a) Absolute configuration (R/S system) (b) Relative configuration (D/L system)

l

Determination of R/S configuration : Rule-1

Assign the priority to the four groups attached to the chiral carbon according to priority rule.

Rule-2

If lowest priority 4 is bonded to vertical line then moving

Rule-3

2

3

Clockwise

R

Anti clockwise

S

If lowest priority 4 is bonded to horizontal line then moving

1 * Where n = number of sites where GI is possible.

H CH3

1 (If n is even)

COOH

2

3

Clockwise

S

Anti clockwise

R

109

CHAPTER

Chemistry HandBook

ALLEN

DETERMINATION OF D/L SYSTEM : • Reference molecule glyceraldehyde • It is used to assign configuration in carbohydrate, amino acid and similar compounds Rule: Arrange parent carbon chain on the vertical line • Placed most oxidised carbon on the top or nearest to top. • On highest IUPAC numbered chiral carbon If OH group on RHS ® D If OH group on LHS ® L H HO H H

CHO OH H OH OH C H 2 –O H

CH O H OH H H CH 2– O H

HO H HO HO

l

l

l

l

l

D – G lucose L– G lu co se CIP SEQUENCE RULE : The following rules are followed for deciding the precedence order of the atoms or groups :(i) Highest priority is assigned to the atoms of higher atomic number attached to asymmetric carbon atom. (ii) In case of isotopes, isotopes having higher atomic mass is given priority. (iii) If the first atom of a group attached to asymmetric carbon atom is same then we consider the atomic number of 2nd atom or subsequent atoms in group. (iv) If there is a double bond or triple bond, both atoms are considered to be duplicated or triplicated.

l

Non-superimposable mirror images are called enantiomers which rotate the plane polarised light up to same extent but in opposite direction. Diastereomers are stereoisomers which are not complete mirror images of each other. They have different physical and chemical properties. Meso compounds are those compounds whose molecules are superimposable on their mirror images inspite of the presence of asymmetric carbon atom. An equimolar mixture of the enantiomers (d & l) is called racemic mixture. The process of converting d- or l- form of an optically active compound into racemic form is called racemisation. The process by which dl mixture is separated into d and l forms with the help of chiral reagents or chiral catalyst is known as resolution. Compound containing chiral carbon may or may not be optically active but show optical isomerism. For optical isomer chiral carbon is not the necessery condition. Calculation of number of optical isomers

l

l

The compound

Optically active forms

Unsymmetrical

2

Symmetrical If n = even

2(n–1)

2 2 –1

Symmetrical If n = odd

2(n–1) – 2(n–1)/2

2(n–1)/2

n

Zero n

* Where n = no. of chiral carbon

CONFORMATIONAL ISOMERISM

Ha Ha

Hc Hc

Ha Hb

Hb Hb

Eclipsed form (lea st stable)

110

Hc

60°

Hc

Hb Ha

Staggered form (m ost stable)

4

l

CH3 CH3

H H

H

CH3

1

H

60° Rotation

H Gauche

CH3 H

CH3

60° Rotation

H H

Fully eclipsed (less stable)

l

3

Conformations of butane : CH3 – CH2 – CH2 – CH3

H

H H

H

CH3

H

60° Rotation

CH3 H

Partially Eclipsed form

H

CH3

H

Anti Staggered-form (most stable)

The order of stability of conformations of n-butane. Anti staggered>Gauche>Partially eclipsed>Fully eclipsed.

l

Relative stability of various conformation of cyclohexane is Chair > twist boat > boat > half chair (Chiral)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

The different arrangement of atoms in space that results from the carbon-carbon single bond free rotation by 0-360° are called conformations or conformational isomers or rotational isomers and this phenomenon is called conformational isomerism. Newmann projection : Here two carbon atoms forming the s bond are represented one by circle and other by centre of the circle. Circle represents rear side C and its centre represents front side carbon. The C–H bonds of front carbon are depicted from the centre of the circle while C–H bond of the back carbon are drawn from the circumference of the circle.

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

111

CH APTER

Chemistry HandBook

ALLEN

REACTION MECHANISM Electrophiles are electron deficient species.

Relative electron withdrawing order (–I order)

eg. H , R , NO , X , PCl 3, PCl5

- N F3 > - N R 3 > - N H 3 > –NO2 > –CN > –COOH

Å

Å 2

Å

Å

Å

Å

Nucleophiles are electron rich species.

> –X > –OR > –OH > –CºCH > –NH2 > –C6H5 > –CH = CH2 Relative electron releasing order (+I order)

e.g. C l, C H 3, O H , R O , C N , N H 3, R O H , C H 2 =CH 2 , C H ºC H

– N H > –O > – C O O >3°alkyl>2°alkyl>1° alkyl>–CH3

RELATIVE STABILITY ORDER (A) Stability of carbocation

ACIDIC STRENGTH µ Stability of conjugate base

Å

( N H4 and H3 OÅ are not electrophile)

Å

Å

Å

> (Ph)3 C > (Ph)2 CH > Ph - CH2 > CH2 = CH - CH2 > Å

Å

Å

Å

Å

Å

(CH3 )3 C > (CH3 )2 C H > CH3 C H2 > C H3 > CH2 = C H > CH º C

(B) Stability of free radical & > (Ph) CH & > PhCH & & (Ph)3 C 2 2 > CH2 = CH - CH2 >

& > (CH ) CH & > CH CH & & (CH3 )3 C 3 2 3 2 > CH3 (C) Stability of Carbanion Q

Q

µ Ka µ

Å

Q

(i) H2O > CH º CH > NH3 (ii) CH º CH > CH2 = CH2 > CH3–CH3 OH

(iii) R–SO3H > R–COOH >

Q

Q

Q

(v)

OH NO2

NO2

(vi) CCl3COOH > CHCl2COOH > CH2ClCOOH (vii) CH –CH –CH–COOH > CH –CH–CH COOH > CH–CH CH COOH 3

•

• •

Basic strength of amine :In aqueous medium R Þ –CH3 2° > 1° > 3° > NH3 R Þ –CH2CH3 2° > 3° > 1° > NH3 In gaseous medium R Þ –CH3 3° > 2° > 1° > NH3 R Þ –CH2CH3 3° > 2° > 1° > NH3 Reactivity towards nucleophile (NAR) (1) HCHO > CH3CHO > (CH3)2CO (2) CCl3CHO > CHCl2CHO > CH2ClCHO Reactivity order towards acyl nucleophilic substitution reaction Acid chloride > anhydride > ester > amide Order of electronic effect Mesomeric > Hyperconjugation >Inductive effect Stability of alkene µ no. of a-hydrogen

(ix) C6H4

112

Heat of hydrogenation µ

2

2

F

2

2

F

Phenol > m > p > o

OH p > o > m > Phenol

NO2 OH

NO2

OH

NO2

(x)

> NO2

OH

NO2

>

OH NO2

>

NO2

COOH (xi) C6H4

NO2

o > p > m > benzoic acid

COOH (xii) C6H4

CH3

o > benzoic acid > m > p

cis form

RCH=CH2 > CH2=CH2 •

3

OH C H (viii) 6 4 CH3

R2 C=CR 2 > R2 C=CHR > R2 C=CH2 >RCH=CHR > RCH=CHR trans form

2

F

1 BASIC STRENGTH µ Kb µ pK b

•

> H CO O H > C 6 H 5 C O O H > C H 3C O O H

NO2

Q

CH3 > CH3 CH2 > (CH3 )2 CH > (CH3 )3 C

•

> R–OH

(iv) HCOOH > CH3COOH > CH3CH2COOH

(Ph)3 C > (Ph)2 CH > Ph - C H2 > CH2 = CH - CH2 > Q

1 pK a

1 Stability of alkene

(xiii) C6H 4

COOH Cl

o > m > p > benzoic acid

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

Å

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

113

C HAP TE R

Chemistry HandBook

ALLEN

PRACTICAL ORGANIC CHEMISTRY LASSAIGNE'S METHOD (detection of elements)

PURIFICATION METHODS DISTILLATION TECHNIQUES

Type :

(A) SIMPLE DISTILLATION Conditions (i) When liquid sample has non volatile impurities (ii) When boiling point difference is 80 K or more. Examples (i) Mixture of chloroform (BP = 334K) and Aniline (BP = 457K) (ii) Mixture of Ether (b.p. = 308K) & Toluene (b.p. = 384K) (iii) Hexane (342K) and Toulene(384K)

(B) FRACTIONAL DISTILLATION When b.p. difference is 10K Examples (i) Crude oil in petroleum industry (ii) Acetone (329 K) and Methyl alcohol (338K)

(C) DISTILLATION UNDER REDUCED PRESSURE (Vacuum distillation) When liquid boils at higher temperature and it may decompose before b.p. is attained. Example (i) Concentration of sugar juice (ii) Recovery of glycerol from spent lye. (iii) Glycerol (D) STEAM DISTILLATION P = P1 + P2 When the substance is Vapour Vapour Vapour immiscible with water and pressure pressure pressure steam volatile. of of water Example : Organic (i) Aniline is separated liquid from water (ii) Turpentine oil (iii) Nitro Benzene (iv) Bromo Benzene (v) Naphthalene (vi) o-Nitrophenol

Sodium extract Na + C + N D

Element Nitrogen

Confirmed test (NaCN+FeSO4+NaOH) boil and cool +FeCl 3+conc.

NaCN

HCl ® Fe4[Fe(CN) 6]3 Prussian blue colour

(i) Na2S + Na2[Fe(CN)5NO]

2Na + S D

Sulphur

sodium nitrosopruside

® Na4[Fe(CN)5NOS] a deep violet colour

Na2S

PbS¯ Black ppt. NaX + HNO3 + AgNO3

Na + X D

Halogen

(i) White ppt. soluble in aq. NH3 confirms Cl. (ii) Yellow ppt. partially soluble in aq. NH3 confirms Br.

NaX

(iii) Yellow ppt. insoluble in aq. NH3 confirms I. Nitrogen and sulphur together

As in test for nitrogen; instead of green or blue colour, blood red colouration confirms presence of N and S both

Na+C+N+S D NaCNS Sodium thiocyanate (Blood red colour)

Estimation of carbon and hydrogen - Leebig's method CxHy +

x+y y O2 ®xCO2 + H2O 4 2 12

wt. of CO

2 % of C = 44 ´ wt. of org. compd ´ 100

% of H =

2 wt. of H2O ´ ´ 100 18 wt. of org compd

Note : This method is suitable for estimation if organic compound contains C and H only. In case if other elements e.g., N, S, halogens are also present the organic compound will also give their oxides which is being absorbed in KOH and will increase the percentage of carbon and therefore following modification should be made.

114

ESTIMATION OF NITROGEN Kjeldahl's method : Duma's method : In this method nitrogen containing The nitrogen containing organic compound yields nitrogen gas on compound is heated with conc. H2SO4 in heating it with copper (II) oxide in presence of copper sulphate to convert the presence of CO 2 gas. The nitrogen into ammonium sulphate which is mixture of gases is collected over decomposed with excess of alkali to liberate potassium hydroxide solution in ammonia. The ammonia evolved is which CO2 is absorbed and volume of nitrogen gas is determined. æ Vol. of N2 ö ç collected ÷ ç at N.T.P. ÷ % of N = 28 ´ ç ÷ ´ 100 22400 ç Wt. of ÷ organic ç ÷ è compound ø Note : This method can be used to estimate nitrogen in all types of organic compounds

1.4 ×volume (ml) of H 2 SO 4 used for % of N =

Neutralisation ×normality of acid wt of organic compound

Note : This method is simpler and more convenient and is mainly used for finding out the percentage of nitrogen in food stuffs, soil, fertilizers and various agricultural products. This method cannot be used for compound having nitro groups, azo group (–N = N–) and nitrogen in the ring (pyridine, quinole etc.) Since nitrogen in thes e compounds is not quantitatively converted in to ammonium sulphate.

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

QUANTITATIVE ANALYSIS OF ORGANIC COMPOUNDS

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

115

CHAPTER

Chemistry HandBook

ALLEN

DISTINCTION BETWEEN PAIRS OF COMPOUNDS UNSATURATION TEST

DISTINCTION BETWEEN 1°, 2° & 3° ALCOHOLS

(a) Double/Triple bonded Compounds (C = C)/(C º C)+ Br2 in CCl4 (Brown colour) ® Colourless compound

R •

•

Br R – CH – CH – R

R – CH = CH – R + Br2

R – C º C – R + Br2 (Alkyne) (Brown)

•

R – CH – CH – R + MnO2 Brown ppt OH OH

(Cold, dilute)

(Colourless)

• R – C º C – R' + KMnO4 (Alkyne)

(Hot, dilute)

Brown ppt.

MnO2 + RCOOH + CO2 + H2O

R – CH2 – Cl Cloudiness appears after 30 minute

OH

•

H3C – CH – R type of alcohols give iodoform test.

OH

•

H3C – CH – R + I2

NaOH Iodoform test

CHI 3 + RCOONa Iodoform (Yellow ppt.)

OH + FeCl3

•

R – C º CH Terminal alkyne Cu 2Cl2 + NH 4OH

Red ppt.

NATURE OF X-GROUP IN C–X BOND R – OH + KX

3H+ + [Fe(OC6H5)6]3– + 3HCl

Carbonyl + 2, 4-DNP (Bredy's reagent) compound

HNO3 AgNO3

AgX

Precipitate

If X is Cl, precipitate will be white and for Br yellow precipitate will be obtained.

Yellow/orange crystal O2N

NO2 H C = O + N – NH H

NO2

C = N – NH

NO2

(Bredy's reagent)

AgNO 3 + NH 4OH

White ppt.

NH4Cl + H2O + R – C º C – Cu

(neutral )

Violet colouration

Red ppt.

NH4NO3 + H2O + R – C º C – Ag

Phenol + ferric chloride ¾¾® Violet colouration

CARBONYL GROUP

Ammonical cuprous chloride

White ppt.

PHENOL

6

Terminal alkyne Ammonical silver nitrate

116

Lucas reagent Heat

Brown ppt. (Colourless)

TEST FOR TERMINAL ALKYNE

R – CH – Cl Cloudiness appears within five minutes

Lucas reagent is anhydrous ZnCl2 + conc. HCl. HALOFORM REACTION IN ALCOHOL

Baeyer's reagent is cold, dilute KMnO4 solution having pink colour. Note : The above test are not given by Benzene. Although it has unsaturation.

R – X + aqueous KOH

R – CH2 – OH

MnO2 + RCOOH + R'COOH

(Hot, dilute)

• R – C º C – H + KMnO4

R – CH – OH

Primary alcohol

(b) Double/Triple bonded Compounds + Baeyer's reagent (Pink colour) ¾® Brown precipitate

(Alkene)

R Lucas reagent Room temperature

Secondary alcohol

(Colourless)

• R – CH = CH – R + KMnO4

Cloudiness appears immediately

R •

Br Br R–C–C–R Br Br

CCl4

R

Tertiary alcohol

(Colourless)

(Brown)

(Alkene)

R – C – Cl

• All aldehydes and only aliphatic methyl ketones + NaHSO3 ® White crystalline bisulphite (Water soluble). OH R – + R – C – SO 3Na C=O + NaHSO3 H H Aldehyde R H3C

OH C=O + NaHSO3

Methyl ketone

R – C – SO–3Na+ CH3

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

•

R – C – OH R

Br

CCl4

R Lucas reagent Room temperature

E

C HAP TE R

Chemistry HandBook

ALLEN ALDEHYDE GROUP

Chloroethane and chlorobenzene

Aldehyde + Tollen's reagent ¾¾® Silver mirror

•

• C2H5–Cl + aq. KOH

Boil

HNO3 AgNO3

C2H5—OH+KCl

AgCl

White ppt.

O R–C–H + 3OHQ + 2[Ag(NH3)2]+

Q

RCOO + 2H2O + 4NH3 + 2Ag

(silver mirror)

•

Aldehyde + Fehling's solution ® Reddish brown precipitate O R–C–H + 2Cu2+ + 5OH—

RCOOQ + 3H2O + Cu2O

•

Cl + aq. KOH

•

• •

H3C – C – group also give iodoform test

Cl + aq. KOH

Boil

H3C–C–R + I2 + NaOH

CHI3 + RCOONa Iodoform (Yellow ppt.)

• •

AROMATIC ALDEHYDE GROUP Aromatic aldehyde + Tollen's reagent ® Silver mirror Aromatic aldehyde + Fehling's soln ® Negative test

Negative test Ag + Silver mirror

Fehling's solution

• •

•

C2H5–Cl + aq. KOH

Boil

(Chloroethane)

C2H5–Br + aq. KOH

Boil

(Bromoethane)

AgBr

Yellow ppt.

OH CH2 + KCl

Boil

CH2 + aq. KOH

HNO3 AgNO3

AgCl

Boil

Cl + aq. KOH HNO , AgNO No reaction 3

3

Chlorobenzene

H2O + CO32— + Cu2O 2Ag + CO32— + H2O

Ethyl chloride and vinyl chloride •

C2H5 – Cl + aq.KOH

Boil

(Ethyl chloride)

Carbylamine reaction

Isonitrile Primary + KOH + CHCl3 (Offensive smell) amine Amines (1°, 2° & 3°) (Hinsberg's test) • Primary amine + Benzenesulphonyl chloride KOH ® Precipitate ¾¾¾ ® soluble

C2H5 – OH + KCl AgCl

(White ppt.)

AMINES (1°)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

AgCl

White ppt.

HNO3 AgNO3

C2H5–OH+KBr

White ppt.

Silver mirror

E

HNO3 AgNO3

C2H5–OH+KCl

(Benzyl chloride)

CHO

Red ppt.

Tollen's reagent

No reaction

Cl

•

Fehling's solution

HCOOH

Boil AgNO3 , HNO 3

AgCl

White ppt.

Benzyl chloride and chlorobenzene

FORMIC ACID

Formic acid

Cl + aq. KOH

Tollen's reagent

COO—

HNO3 AgNO3

OH + KCl

Chloroethane and bromoethane

O Iodoform test

No reaction

Chlorocyclohexane and chlorobenzene

(Reddish brown ppt)

O

Boil AgNO3 , HNO 3

•

H2C=CH–Cl + aq.KOH

HNO3 AgNO3

Boil HNO 3, AgNO 3

No reaction

Vinyl chloride

n-Propyl alcohol and iso-propyl alcohol •

ZnCl2 CH3 CH 2CH2OH + HCl ¾¾¾® CH 3CH2CH2 Cl

No cloudiness at room temp.

•

Secondary amine + Benzenesulphonyl chloride KOH ¾® Precipitate ¾¾¾ ® insoluble

•

Tertiary amine + Benzenesulphonyl chloride ® No reaction

Note : Benzenesulphonyl chloride is called Hinsberg's reagent.

•

OH H3C–CH–CH3

ZnCl2 HCl

Cl H3C–CH–CH3 Cloudiness within 5 minutes

Ethyl alcohol and methyl alcohol (Iodoform test) •

CH3CH2OH + 4I2 + 6NaOH ¾® CHI3 + HCOONa

•

CH3OH + 4I2 + 6NaOH ¾¾® No yellow ppt.

Yellow ppt.

117

CHAPTER

Chemistry HandBook

ALLEN

Ethyl alcohol and acetone (By 2, 4 – DNP)

H3C H3C

O2N C=O+

H N – NH H

Acetone

•

H3C H3C

•

O

NO2

H3C – CH2 – CH + 3OH—+ 2[Ag(NH3)2]+

2, 4-Dinitrophenylhydrazine

O2N

— CH3CH2COO + 2H2O + 4NH3 + 2Ag¯

(Silver mirror)

NO2

C = N – NH

•

(yellow orange crystals)

2,4 - DNP ® No reaction C2H5OH ¾¾¾¾¾

•

Propanal and propanone (Tollen's and Fehling reagent) Propanal + Tollen's reagent ¾¾® Silver mirror

Propanal + Fehling's solution ® Reddish brown precipitate O

Phenol and ethyl alcohol (Neutral FeCl3) • Phenol + Neutral ferric chloride ® Violet colouration

H3C – CH2 – CH + 2Cu2++ 5OH— CH3CH2COO— + 3H2O + Cu2O

(Reddish brown ppt.)

6

OH + FeCl3

3H + [Fe(OC6H5)6] + 3HCl +

3–

Violet colouration

•

Propanone

• CH3CH2OH + Neutral ferric chloride ® No violet color Benzoic acid and phenol (NaHCO 3) • Benzoic acid + Sodium bicarbonate ® effervescence C6H5COOH +NaHCO3 ® C6H5COONa + CO2­+H2O •

Fehling's solution

Negative test

Tollen's reagent

Negative test

Pentan-2-one and pentan-3-one (Iodoform test) O

• H3C – CH2 – CH2 – C – CH3 + I2 + NaOH Iodoform test (Pentan-2-one)

Phenol + Sodium bicarbonate ® No effervescence

CHI3 + CH3CH2CH2COONa

(Phenol is less acidic than benzoic acid)

Iodoform (Yellow ppt.)

Propanone and propanol (2, 4 - DNP) O

H3C

C=O+

H N – NH H

NO2 2, 4-DNP

• H3C H3C

Propanal and benzaldehyde (Fehling solution) • Propanal + Fehling's solution ® Reddish brown ppt

O2N

O 2+

–

H3C – CH2 – C – H + 2Cu + 5OH

NO2

C = N – NH

—

CH3CH2COO + 3H2O + Cu2O

Fehling's solution

•

Yellow orange crystals

Benzaldehyde + Fehling's solution ® No precipitate 2+

•

Ethanal and propanal (Iodoform test)

Ethanal

CHI3 + HCOONa Iodoform (Yellow ppt.)

•

HCOOH Methanoic acid

O

• H3C – CH2 – C – H + I2 + NaOH Propanal

118

Iodoform test

No reaction

Methanoic acid and ethanoic acid (Tollen's & Fehling solution)

O Iodoform test

—

CHO + 2Cu + 5OH

Propanol + 2,4-Dinitrophenylhydrazine ® No crystals

• H3C – C – H + I 2 + NaOH

No yellow ppt.

Pentan-3-one

No yellow ppt.

• Ethanoic acid

Fehling's solution

H2O + CO3

Tollen's reagent

2Ag¯+ CO3

2—

2—

+ Cu 2O + H 2O

Fehling's solution

No reddish brown ppt.

Tollen's reagent

No silver mirror

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

H3C

•H3C – CH2 – C – CH2 – CH3 + I2 + NaOH Iodoform test

O2N

E

CHAPTER

Chemistry HandBook

ALLEN Ethanal and methanal (Iodoform test) •

CH 3CHO + I2 + NaOH

Iodoform test

Ethanal

•

Aniline and N-methylaniline (Isocyanide test)

CHI 3 + HCOONa Iodoform (Yellow ppt.)

HCHO + I2 + NaOH

Iodoform test

•

•

O

NH – CH3 + CHCl3 + 3KOH (alc.)

N-Methylaniline

Iodoform test

NH2

•

CHI3 +

COONa

(Yellow ppt.)

Aniline

N=N

+ I2 + NaOH

C

Iodoform test

No ppt.

OH

Mild Basic Medium

•

effervescence

Ethyl benzoate + Sodium bicarbonate ® No effervescence

Benzaldehyde and acetophenone (Tollen's test) • Benzaldehyde + Tollen's reagent ® Silver mirror

NaNO2 + HCl

CH2 – OH

(Tollen's reagent)

COO + 2H2O + 4NH3 + 2Ag¯ —

Acetophenone + Tollen's reagent ® No silver mirror

Methyl amine and dimethyl amine (Isocyanide test) • CH3NH2 + CHCl 3 + 3KOH (alc.)

Glucose and fructose •

Glucose+ Br2 + H 2 O ® Gluconic acid + 2HBr

•

Fructose+ Br2 + H 2 O ® No change in color

( brown )

( colorless )

( brown )

CH3NC + 3KCl + 3H2O

•

Glucose + Tollen's reagent ¾¾® Silver mirror

•

Sucrose + Tollen's reagent ¾¾® No silver mirror

Glucose and starch •

Glucose + Fehling's solution ¾¾® Red ppt.

•

Starch + Fehling's solution ¾¾® No red ppt.

Methyl isocyanide (Offensive smell)

OR

CH3

• H3C–NH + CHCl3 + 3KOH(alc.)

OH

No orange dye

Glucose and sucrose

CHO + 3OH— + 2[Ag(NH3)2]+

Methyl amine

CH2 – NH2 Benzylamine

Benzoic acid and ethylbenzoate •C6H5COOH + NaHCO3 ® C6H5COONa + CO2­+ H2O

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

OH

N2Cl

Diazotisation 0–5°C

Orange dye

(Benzophenone)

E

+ –

NaNO 2 + HCl

O

•

No offensive smell

Aniline and Benzylamine (Diazotisation + phenol)

C – CH3 + I2 + NaOH (Acetophenone)

•

P heny l isoc ya nide (O ffe nsiv e sm ell)

No yellow ppt.

Acetophenone and benzophenone (Iodoform test)

•

N C +3 KC l+3H 2 O

(alc.)

A niline

Methanal

•

N H 2+C H C l 3+3KO H

No offensive smell

Di-methyl amine

•

Glucose + I2 solution ¾¾® No blue colour

•

Starch + I2 solution ¾¾® Blue colour

Aniline and ethyl amine (Diazotisation) NH2

• Aniline

NaNO2 + HCl Diazotisation 0–5°C

N=N

OH

+ –

N2Cl

Mild basic medium

OH

Orange dye p-hydroxy azobenzene

• CH3CH2NH2

NaNO 2 + HCl

OH CH3CH2OH

No Orange dye

Ethyl amine

119

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

Chemistry HandBook

120 ALLEN

IMPORTANT NOTES

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

121

Chemistry HandBook

CH APTER

ALLEN

HYDROCARBON

• • •

Reactivity of alkane towards free radical halogenation is µ stability of free radical C6H5–CH3>CH2=CH–CH3 >(CH3)3CH > CH3–CH2–CH3>CH3–CH3>CH4 Reactivity of halogen towards free radical substitution F2 > Cl2 > Br2 > I2 Knocking tendency of petroleum as fuel decrease with increase in side chain. Straight chain > Branched chain Knocking tendency is in the order Olefin > cycloalkane > aromatic

122

•

Boiling point decrease with increase in number of side chain. CH3–CH2–CH2–CH2–CH3 > normal

CH3 > C H 3 – CH – C H 2 – C H 3 > C H 3 – C – C H 3 CH3 CH3 iso

neo

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALKANE

E

CHAPTER

Chemistry HandBook

ALLEN

R CH OH

PREPARATION

H 2SO 4/D or

CH3

H2/Pd-CaCO 3

H 3PO 4/D or Al2O 3/D

X R CH2 CH2 X CH2

X R CH X

Na/Liq. NH 3

Alc. KOH -HX

Birch Reduction give trans Alkene

D

H

(Markownikov's rule)

O H H3C CH CH3

Less substituted alkene is major product

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

E

O H H3C CH CH2 Br Cl H3C CH CH2 Br I H3 C CH CH2 Br

H3 C

HO OH H3 C CH CH2

or dil. Alk. KMnO4 (Bayer's Reagent)

(EAR)

(S yn addition)

O

½O2 /Ag/D or H3CCO3H

H3C CH

CH2

H2O 2

Epoxidation

(EAR)

O

CH2

H H

Dry NaCl

+ Br

H or OH

(EAR)

Anti addition of Br2

d-

Cl

Cl CH2 CH

(FRSR)

cis ® d,l dibromide trans ®meso dibromide Markownikoff Rule (M.R.)

Br

NBS (FRSR) High temp. / Pressure Catalysts

d-

d+

N O

HBr+R2O 2

(FRAR)

(Anti-Markownikov's rule)

(Markownikov's rule)

H3 C CH2OH

+ H3 C

OH

CO2+H2O

combustion Cl2/500°C

I

(Anti addition)

O O H3C C H+ H C H O H3C C OH+CO2

CH3COOH+CO2

3n 2 O2

Br2

CH2

d+

OH CH2

+

KMnO4 D

H3C CH

H 2O2

O LiAlH 4

(EAR)

Br CCl4

KI

H3C CH

H3C CH 18 OH

H 2O/Zn

B 2H 6/THF

( CH3 CH CH2 )3B H

O

H+ /H 2O18

O

O3

(EAR)

CH CH2 Cl OH

OsO4/NaHSO3

X

NaBH 4

NaOH

CH2 Br

O Cl

(EAR)

Hg(OAc )2

(No rearrangement )

Br H3C CH

d- d+

H

(EAR)

O H H3C CH CH3

H OH H3 C CH CH2

REACTIONS

H+ /H 2O

Intermediate :carbocation (thus rearrangement occurs)

Å

(CH3-CH2)4NOH

Hoffman Rule

Cold Conc. H2SO 4 (EAR)

HBr, HCl, HI

b

H3C–CH2–CH=CH2

Saytzeff Rule

X H3C CH CH3

a

D

Elimination Reaction E1 & E2 H H a H3C–CH–CH–CH2 b b Y

more substituted alkene is major product

H

H O R C O CH2 CH R

Pyrolysis D

Zn dust For Higher Alkene

H3C–CH=CH–CH3

HOO 2SO

R–C º C–R

Zn dust

Kolbe electrolysis

CH 3–CH–CH2

R–C º C–R

Lindlar Catalyst give cis Alkene

(X:Cl, Br,I)®Saytzeff's Rule

X R CH

Partial reduction

ALKENE

Br

HBr

HBr Peroxide

Br

CH2

(Allylic halogenation)

Br CH2 CH CH2 (Allylic halogenation) —CH—CH ( )n 2—

Polymerisation

CH3 CH 3CH2CH2Br

(Anti-Markownikov's rule)

Rate of EAR : R2C=CR2 > R2C=CHR > RCH=CHR > R—CH2=CH2> CH2=CH2

•

Order of reactivity of olefins for hydrogenation CH2=CH2 > R–CH=CH2 (Reverse of stability)

•

Order of reactivity of alkene towards hydration C H 3 – C = C H 2 > CH3–CH = CH2 > CH2 = CH2 CH3

123

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

(EAR)

124 oxidation

Elimination

Chemistry HandBook C HAP TE R

ALLEN

ALKYNE

Kolbe's electrolysis

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

CHAP TER

ALLEN

E Chemistry HandBook

BENZENE

125

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

Chemistry HandBook

126 ALLEN

IMPORTANT NOTES

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

127

C HAP TE R

Chemistry HandBook

ALLEN

PREPARATION

HALOALKANE

H3C CH2 CH2 CH3 Corey house synthesis

H3C CH2 NH2 H3C CH2 C C H

NaI Acetone (C2H5)2CuLi NH3 excess + H C CNa

Wurtz reaction

OH Aq KOH Moist Ag2O

Na Et2O

H3C CH2 CH2 CH3

Br

Wurtz-Fittig Reaction

H3C CH2

Na/Et2 O Mg/Et2 O

C2 H5 MgBr

KCN EtOH

Alc. KOH

H2C CH2

Ag-O-N=O

NaBH4/EtOH---->2° & 3° not 1° R—X

CH3–CH 2–ONO

NaNO2

H3C CH2

NaSH Alc.

SH

+

H3C CH2 N C

—

K O N=O

LiAlH4/Et2 O

(1°,2° not 3° R—X)

H3C CH2 C N

AgCN

+

H3C CH2 H

H3C CH2 OH

H3C CH2 O N O O H3C CH2 N O

AlCl3

CH2 CH3

DMF

F.C. Alkylation

C2H5 O C2H5 (R–Br ® 1°)

CH3-CH2ONa+

PHYSICAL PROPERTIES

H3C CH2

RMgX ¾

RCOO

>

>

Br

128

CH3SNa

S CH3

Br

Br

R–R

RCOOCH3

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

H3C CH2 I

(Reactivity order) (R–I>R–Br>R–Cl>R–F)

CH3—X CH3–CH2—X R–X

Reaction with metal

REACTIONS

Nucleophilic substitution S N1 : 3>2>1 S N2 : 1>2>3

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

C HAP TE R

ALLEN

E Chemistry HandBook

TRI-HALO ALKANE

129

CHAPTER

Chemistry HandBook

ALLEN

GRIGNARD REAGENT REACTION GRIGNARD REAGENT as Nucleophile O

O

O R C O H

O H

(1°) R CH2

H3C

O H

C

C

R

RMgX in

OH R C R R

R C Cl excess/ H 3O +

R

R

H 3O +

C

O

RMgX in

H 3O +

–d +d

RMgBr

O H

OH R CH2 CH2

OEt

C

G.R. 1eq.

OMgBr H C R R

O R C R

N

H 3O+

O H

Å

H O R CH CH2 R

O R

C OEt excess

CH

RMgX inH

CH2 3O

+

O R

C

O2

OEt

1eq. RMgX

O C

O H (3° Alc.) R C R R O R C Cl

R O H

H 3O+ O

OEt

O H R C R R

Cl C Cl RMgX in excess /H 3O +

OEt + H 3O + G.R. (excess)

O Cl

C

Cl

Cl

1 eq.

C

N

R C N + Mg

RMgX

O

O

Cl

R C R

C

Cl

2 eq.

Cl

NH 2

R NH2 + Mg

RMgX

GRIGNARD REAGENT as BASE (Active H-containing compound) H

Mg(OH)Br + R-H Mg(OR)Br + R-H Mg(OD)Br + R-D

H

O

H

R

O

H

D

O

D

H

N

R

H

N

R

RMgBr C O

NH 2

R H + Mg

–d +d

R'

H

R H + Mg

R

C

MgBr +R-H Mg(NH2)Br+R-H

H

NH R Br NR2 Br

R H + R' C CMgBr O

O

R H+

MgBr O

130

Br Cl Br Cl

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

O R C R

O R C R

Cl

O

O H R C R R

H3O +

C

1eq. RMgX

H3O+

O H C R OH R CH R

R

O

O H (2°) R CH CH 3

(3°)

O H

C

H 3O +

OH

OH R C R R

R C OEt RMgX in excess/H O+ 3

C O H 3O +

E

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

ALLEN

E Chemistry HandBook

IMPORTANT NOTES

131

CHAPTER

Chemistry HandBook

ALLEN

ALCOHOL (EAR)

Pd+H2 or LiAlH4/NaBH4 H2 O

GMP Hg(OAc)2 /H2O

CH2=CH2

CH3MgX

CH3–CH–CH3

LiAlH4

CH3 | CH3— C—CH=CH2 | CH3

H2O2/NaOH

(1° Alc.)

dil. H2SO4

CH3 | C—CH—CH3 CH— 3 | | OH CH3 (3° Alc.)

Hg(OAc)2/H2 O NaBH4

CH3 | CH3— C— CH—CH3 | | CH3OH (2° Alc.)

Å

O

OH 2° H3C C CH3 H

O CH2 CH2

Grignard Reagent

CH3—C—H H3O

OH | 3°CH3—C—CH3 | CH3

+

H3O

CH3MgBr

(NAR)

O2/60°C

(NAR)

O

O

O

O

CH3—C—Cl

H

(SNAE) Et2 O Mg (dry)

O Et

(SNAE)

C OEt (SNAE)

CH3—Br Aq. KOH Moist Ag2 O

• •

132

2CH3OH

H3O CH3 C

3

CH3 CH2 CH CH3

H3 O +

+

CH3 —C—CH3

3

OH

O

O

OH | CH MgBr 3°CH—C—CH + 3 3 HO | (NAR) CH3

CH—CH 2—CH—OH 2 3

+

CH2 CH CH3

(NSR)

O O MgBr H—C—H H3C C H + HO 3 H

(NSR)

+

(NAR)

1°CH3–CH2–OH

H3O

O

LiAlH4 H2 O

(ii) Zymase

(CH3)3C—CH—CH2 | | H OH

CH–C–OH 3

H2O

(i) Invertase

B2H6/THF

CH3–C–Cl O

OH R–OH

(NAR)

H2 O

C12H22O 11+H2O sucrose

CH–C–CH 3 3 O

LiAlH4/NaBH4 H2O

CH3–CH2–CH2–OH

H2O2/NaOH

CH3–CHO

H2O

CH3–CH2–OH

(EAR)

B2H6/THF

Pd+H2 or LiAlH4/NaBH4

CH3–OH

NaBH4

O CH3 C

O H3 C

C

OH CH3MgBr CH3 H O+ CH3 C CH3 3 CH3 (NAR)

H

CH3MgBr + H3O

(NAR)

H3C

CH OH

CH3

CH3—OH

Solubility of alcohol increase with increase in branching n < iso < neo (isomeric) Relative order of reactivity (i) 1° > 2° > 3° (O–H bond fission) (ii) 3° > 2° > 1° (C–O bond fission) (iii) 3° > 2° > 1° (Dehydration)

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

CH2=CH2

CH–CHO 3

Reduction

Dil. H2SO4

CH2=CH2

E

CHAPTER

Chemistry HandBook

ALLEN

ALCOHOL

(NSR)

HCl+SO2+CH3—CH2—Cl + SO2+CH3—CH2—Cl

CH3—CH2—O—CH2—CH3 CH2=CH2

CH3MgBr

PCl3

CH4+CH3—CH2OMgBr

O

O

(SNAE) CH3—C—OH Conc. H2SO4

PBr3 SOCl2 SOCl2/

HI or KI/H3PO4

O (CH3—C)2O (SNAE) HCl/ZnCl2 Lucas Reagent

NH3 Al2O3

170°C

620 K

H2SO4

CH2=CH2

(Elimination)

(i) Na (ii) CH3—CH2—I (1°)

100°C

CH3—CH2—Br [3° R—O—H ® Alkene]

CH3—CH2—NH2

Al2O3 Conc. H 2SO4

O CH3—C—O—CH2—CH3 CH3—CH2Cl

HBr or NaBr + H2SO4

H2SO4/D/140°C

CH3—CH2HSO4

CH3—C—O—CH2—CH3

(NSR)

CH3—CH2—I

Å

CH3CH2—ONa

Estrification

H3PO3+3CH3—CH2—Br

Na

CH3—CH2—OH

H3PO3+3CH3—CH2—Cl

PCl5

Acid base reaction

POCl3+CH3—CH2—Cl

CH3CH2—O—CH2—CH3

DEHYDROGENATIONS OH H 3C

Reagent

H3C CH2 CH CH3

CH2 CH2 CH2

H3C CH2 CH2 C

Å

H

H3C CH2 C CH3 O

O H 3C C H 2 C H 2 C

Jo ne s Rea gent

OH

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

O

No reaction No reaction

H3C–C–OH+CH3–C–OH

O

E

CH3 3° Alcohol

O

O

K 2C r2 O 7 / H KMnO 4 /H + /O H/ D

H3C–C–OH

2° Alcohol

1° Alcohol PCC/PDC Anhy. CrO3

CH3

OH

CH3

O

Cu/300°C

H3C CH2 CH2 C

Lucas Reagent HCl/ZnCl2

Cloudiness appear upon heating after 30 mins.

H

CH3 CH2

C

CH3

H3C

within five min.

CH2

C

Immediately

VICTOR MEYER'S TEST P/I2

CH3–CH2–CH2–CH2–I

CH3

CH3 H3C CH2 CH I

H3C

C

I

CH3

CH3

AgNO2

CH3–CH2–CH2–NO2

H3C HNO2

NaOH

CH2 C

NO2

CH2 CH

NO2

N OH Nitrolic acid

Red Color

H3C

(CH3)3C–NO2

CH3 H3 C

CH2 C N

NO2

(No reaction)

O

Blue colour

Colourless

133

C HAP TE R

Chemistry HandBook

ALLEN

GMP

Reactions

ETHER

2 C2H5 OH

H 2SO 4 /140°C

[Williamson continuous etherification]

Cl2 Dark

(NSR) [SN2] +

H3C CH2 ONa

[Williamson synthesis] [3°[R–X] ® Alkene]

CH 3—CH 2—I

(NSR) [SN 2]

HCl

H3C CH2 O CH2 CH3

Cold

H3C CH2 O CH3 Dry Ag2O

2C2H5I

CH 2N 2/BF3 ,

CH3—CH2—OH

D

SO3Na (i) NaOH (ii) H

HI/cold

R O R

(NSR)

HI/D excess

GMP

Å

(i) O2 + D (ii) H Å/H2O

CH3 H3C C H

(–CH3COCH3) other product

+

N2Cl

H2O/D

OH Cl H 2O Industrial method

(i) O2/60°C/D (ii) H 2O/H

COOH OH

+

PHENOL H

NaOH+CaO/D

O 2, V2O5 300°C

OCH3 Br +

OCH3 CH3 +

OCH3 Br2 in CH3COOH Bromination

CH3COCl AlCl3

AlCl3 /CH3Cl Friedel-crafts reaction

OCH3

Friedel-Crafts reaction

Br OCH3

CH3

134

OCH3

OCH3 COCH3 +

conc. H2SO4

Anisole

conc. HNO3

OCH3 NO2

COCH3 OCH3 +

(nitration)

NO2

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

MgBr

E

C HAP TE R

Chemistry HandBook

ALLEN

O

60°C

C

OH

CH3

PHENOL

O

Fries Rearrangement

O C CH3 H3C

C

O Na+

Reactions

O Cl

NaOH

CH3I

SNAE

H—O C CH3

O CH3

120°C

OH NH2

O

O CH3

CH2N2 BF3

NH3

H

ZnCl 2/300°C Zn

3HCl+ [(Ph3O)6Fe]3Violet Colour

No effervescence

FeCl3 Neutral

D

Cl

PHENOL PCl5

NaHCO3

+ (Ph O)3PO

(major) Triphenyl phosphate

O

+ ONa

Ph

NaOH Na2CO3

C

O O C Ph

Cl

Schotten Baumann Reaction

O

OH O2N

NO2

+ O

OH

Conc. HNO3+H2SO4

NaOH Blue

N O

OH O C

Kolbes Schimdt Reaction

OH

H2SO4 Libermann nitroso test

125°C CO2/NaOH H

+

OH HO C O

Z:\NODE02\B0B0-BA\HAND BOOK CHEMISTRY\ENG\3_ORGANIC.P65

N N

E

CCl4 NaOH

OH

O C

OMe

MeOH Å

H

OH O C

Oil of wintergreen O

Ac C OH O

Aspirin

Å

N NCl

Orange dye

HO

Mild basic medium

O

CH3–C–Cl

O

OH

CO2/NaOH 125°C

O O

O

O

Na2Cr2O7 H2SO4

OH Br

+

CS2

NaNO2

H2SO4

Green

OH

Br2

REACTION DUE TO BENZENE RING

excess

HNO3

NO2

OH H2 O

2,4,6-Tribromophenol (White ppt) Br

OH

Red

Br

H2O

NO2

(major)

Br

Br2

Br

OH

OH

conc. HNO3

SO3 H

Conc. H2SO4

O2N

100°C

NO2

NO2

SO3H OH Å CH2 =O + H

OH CH2OH

+

NaOH D

Bakelite polymer

CH OH 2

OH O C

CHCl3

H Reimer Tiemann Reaction

NaOH

HCN+HCl

OH O C

OH H

H3O+ O

Gatterman Reaction

CHO

(major)

C C

+

O

O conc. H2SO4

CO2/NaOH 125°C/H +

Phenolphthalein

OH O C

NaOH

(Pink colouration)

OH Ph-OH POCl3

Phenyl salicylate

135

C HAP TE R

Chemistry HandBook

ALLEN

A

REACTIONS Kinetics

Comparision of E1 and E2

SN1 1st order

SN2 2nd order

REACTIONS A Kinetics B C

B

Rate

k[RX]

k[RX][Nu:Q]

C

Stereochemistry

Racemisation

Inversion

D

3°> 2°>1°>MeX

MeX >1°>2°>3°

E

Substrate (reactivity) Nucleophile

F

Solvent

Rate Independent Good in protic

Needs Strong Nu Faster in aprotic

G

Leaving Group

Needs Good LG

Needs Good LG

H

Rearrangement

Possible

Not Possible

E1 1 order

E2 2 order

Rate

k[RX]

Stereochemistry

No special geometry 3° > 2°>>>1°

k[RX][B: ] Antiperiplanar 3° >2° >1°

D

Substrate

E

Base Strength

F

Solvent

G

Leaving Group

H

Rearrangement

Summary of SN1, SN2, E1 and E2 Reactions RX 1°

Mechanism S N2 E2

2°

3°

Q

Q

Nu / B

Better NuQ Aq. KOH, ORQ Strong & bulky base Alc. KOH, (CH3)3COQ

Polar aprotic

Temp. Low

nd

—

Rate Independent Good ionizing

Needs Strong bases Polarity not import Needs Good LG Not Possible

Needs Good LG Possible

Order of reactivity of Alkyl Halide towards S N1 µ Benzylic > Allylic > 3°>2°>1°

High

SN1 µ Stability of carbocation

Low

SN2 µ 1° > 2° > 3°

S N2

Aq. KOH

E2

ORQ , (CH3)3COQ

(SN1)

Solvent

(E1)

Solvent

S N1

Solvent

Protic

Low

R–I > R–Br > R–Cl > R–F

E1

Solvent

Protic

High

E2

NuQ/Base

—

High

With increase in number of strong electron withrawing

Primary (1°)

136

Solvent

st

Polar aprotic Polar protic

Secondary (2°) SN2 + E2 (if weak base, SN2 favored)

High (Low) (High)

Tertiary (3°)

Strong nucleophile

SN2 >>E2

Weak nucleophile weak base

Mostly SN2

Mostly SN2/SN1

Mostly SN1 at low T mostly E1 at high T

Weak nucleophile strong base

Mostly E2

Mostly E2

E2

E2

SN2 µ

1 Steric hindrance

Reactivity order towards SN1 or SN2 and E1 or E2

group at ortho and para position, reactivity of X towards aromatic nucleophilic substitution increases. Cl

Cl

Cl NO2