12C05
Surface Chemistry
Learning Objectives
Adsorption
Catalysis
Colloids
12C05 - Surface Chemistry
Introduction to Surface Chemistry
Surface Chemistry
It deals with phenomena that occur at the surfaces or interfaces
Surface Chemistry
It deals with phenomena that occur at the surfaces or interfaces
Separating the bulk phases
Surface Chemistry
It deals with phenomena that occur at the surfaces or interfaces
Types of Interfaces
Separating the bulk phases
ConcepTest
Ready for challenge
7
Q. : Why does a gaseous mixture not possess an interface ?
Pause the Video
(Time Duration : 01 Minutes)
Q. : Why does a gaseous mixture not possess an interface ?
Q. : Why does a gaseous mixture not possess an interface ?
Sol. :
Q. : Why does a gaseous mixture not possess an interface ?
Sol. : Gases are completely mixed with each other.
Due to complete miscibility, there is no
interface in mixtures of gases
Phenomena at Interface
Crystallisation
Phenomena at Interface
Crystallisation of water
Crystallisation
Phenomena at Interface
Crystallisation of water
Ice
Crystallisation
Phenomena at Interface
Crystallisation of water
Ice
Medicines
Crystallisation
Phenomena at Interface
Crystallisation of water
Sugar
Ice
Medicines
Crystallisation
Phenomena at Interface
Crystallisation of water
Table salt
Sugar
Ice
Medicines
Dissolution
Phenomena at Interface
Dissolution
Phenomena at Interface
Dissolution of Table Salt
Dissolution
Phenomena at Interface
Dissolution of Table Salt
Dissolution of Medicine
Corrosion
Phenomena at Interface
Corrosion
Phenomena at Interface
Surface of Iron
O2
H2O
Corrosion
Phenomena at Interface
Surface of Iron
O2
H2O
Rusted Iron Object
Phenomena at Interface
Heterogeneous catalysis
Phenomena at Interface
Heterogeneous catalysis
Surface of Catalyst, Ni
Reactant, vanaspati oil
Product, vanaspati ghee
Phenomena at Interface
Heterogeneous catalysis
Surface of Catalyst, Ni
Reactant, vanaspati oil
Product, vanaspati ghee
Surface chemistry
Colloids
Catalysis
Adsorption
12C05.1
Adsorption and its types
12C05.1 Adsorption and its types
Learning Objectives
Absorption and Adsorption
Mechanism of Adsorption
Types of Adsorption
Characteristics of Physisorption
Characteristics of Chemisorption
31
12C05.1
CV 1
Absorption and Adsorption
12C05.1 Adsorption and its types
33
Absorption
12C05.1 Adsorption and its types
34
Absorption
12C05.1 Adsorption and its types
35
One Substance is uniformly distributed throughout the bulk of the other substance
Absorption
12C05.1 Adsorption and its types
36
Adsorption
12C05.1 Adsorption and its types
37
Adsorption
Accumulation of molecular species at the surface of a solid or liquid
12C05.1 Adsorption and its types
38
Adsorbent
Accumulation of molecular species at the surface of a solid or liquid
Adsorption
Adsorbate
12C05.1 Adsorption and its types
39
Adsorbent
Accumulation of molecular species at the surface of a solid or liquid
Adsorption
Adsorbate
Accumulates at the surface
Solid, liquid or gas
12C05.1 Adsorption and its types
40
Adsorbent
Provides Surface for adsorption
Accumulation of molecular species at the surface of a solid or liquid
Solid or liquid
Adsorption
Adsorbate
Accumulates at the surface
Solid, liquid or gas
12C05.1 Adsorption and its types
41
Absorption vs Adsorption
12C05.1 Adsorption and its types
42
Absorption vs Adsorption
Absorbed
Particle
(In the bulk)
Liquid
Gas Particles
12C05.1 Adsorption and its types
43
Absorption vs Adsorption
Absorbed
Particle
(In the bulk)
Liquid
Absorption (bulk phenomenon)
Gas Particles
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44
Absorption vs Adsorption
Absorbed
Particle
(In the bulk)
Adsorbed
Particle
(At surface)
Adsorbent Surface
Gas Particles
Gas Particles
Liquid
Absorption (bulk phenomenon)
12C05.1 Adsorption and its types
45
Absorption vs Adsorption
Absorbed
Particle
(In the bulk)
Adsorbed
Particle
(At surface)
Adsorbent Surface
Adsorption (surface phenomenon)
Gas Particles
Gas Particles
Liquid
Absorption (Bulk phenomenon)
12C05.1 Adsorption and its types
46
Absorption vs Adsorption
Absorption
12C05.1 Adsorption and its types
47
Absorption vs Adsorption
Absorption
Adsorption
12C05.1 Adsorption and its types
48
12C05.1 Adsorption and its types
49
Water vapours are adsorbed by silica gel
12C05.1 Adsorption and its types
50
Water vapours are absorbed by anhydrous CaCl2
Water vapours are adsorbed by silica gel
12C05.1 Adsorption and its types
51
Examples of some common adsorbents :
12C05.1 Adsorption and its types
52
Examples of some common adsorbents :
Charcoal
12C05.1 Adsorption and its types
53
Examples of some common adsorbents :
Charcoal
Silica gel
12C05.1 Adsorption and its types
54
Examples of some common adsorbents :
Charcoal
Silica gel
Alumina gel
12C05.1 Adsorption and its types
55
Adsorption in action
12C05.1 Adsorption and its types
56
Adsorption in action
Brown coloured NO2 gas
12C05.1 Adsorption and its types
57
Adsorption in action
Brown coloured NO2 gas
Activated charcoal
12C05.1 Adsorption and its types
58
Adsorption in action
Brown coloured NO2 gas
NO2 gas adsorbed by charcoal
Activated charcoal
Brown colour is disappeared
12C05.1 Adsorption and its types
59
Adsorption in action
12C05.1 Adsorption and its types
60
Adsorption in action
Gas Molecules
Molecules collide with wall and create pressure
12C05.1 Adsorption and its types
61
Adsorption in action
Gas Molecules
Pressure of gas = P
Molecules collide with wall and create pressure
12C05.1 Adsorption and its types
62
Adsorption in action
Gas Molecules
Adsorbent
Molecules collide with wall and create pressure
Pressure of gas = P
12C05.1 Adsorption and its types
63
Adsorption in action
Gas Molecules
Adsorbent
Molecules collide with wall and create pressure
Pressure of gas = P
Gas adsorbed by Adsorbate
12C05.1 Adsorption and its types
64
Adsorption in action
Gas Molecules
Pressure of gas = P
Pressure of gas < P
Molecules collide with wall and create pressure
Adsorbent
Gas adsorbed by Adsorbent
12C05.1 Adsorption and its types
65
Some basic terms related to adsorption
12C05.1 Adsorption and its types
66
Some basic terms related to adsorption
Desorption
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67
Some basic terms related to adsorption
Desorption
Process of removing adsorbate from surface of adsorbent
12C05.1 Adsorption and its types
68
Some basic terms related to adsorption
Desorption
Process of removing adsorbate from surface of adsorbent
Sorption
12C05.1 Adsorption and its types
69
Some basic terms related to adsorption
Desorption
Process of removing adsorbate from surface of adsorbent
Sorption
Adsorption and absorption take place simultaneously
12C05.1
CV 2
Mechanism of Adsorption
12C05.1 Adsorption and its types
71
Mechanism of Adsorption
Two Aspects
12C05.1 Adsorption and its types
72
Mechanism of Adsorption
Net force on particle
Two Aspects
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73
Mechanism of Adsorption
Net force on particle
Thermodynamics of Adsorption
Two Aspects
12C05.1 Adsorption and its types
74
Net Force on Particle
12C05.1 Adsorption and its types
75
Net Force on Particle
Adsorbent
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Bulk particle
Net Force on Particle
Adsorbent
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Adsorbent
Bulk particle
Surface particle
Net Force on Particle
12C05.1 Adsorption and its types
78
Adsorbent
Bulk particle
Balanced force
Net force = 0
Surface particle
Net Force on Particle
12C05.1 Adsorption and its types
79
Adsorbent
Bulk particle
Balanced force
Net force = 0
Surface particle
Imbalanced force
Net Force on Particle
12C05.1 Adsorption and its types
80
Adsorbent
Bulk particle
Balanced force
Net force = 0
Surface particle
Imbalanced force
Net Force on Particle
Net force
12C05.1 Adsorption and its types
81
Adsorbent
Bulk particle
Balanced force
Net force = 0
Surface particle
Imbalanced force
Other particle
Net Force on Particle
Net force
12C05.1 Adsorption and its types
82
Adsorbent
Bulk particle
Balanced force
Net force = 0
Surface particle
Imbalanced force
Other particle
Net Force on Particle
Net force
Attraction
12C05.1 Adsorption and its types
83
Adsorbent
Bulk particle
Balanced force
Net force = 0
Surface particle
Imbalanced force
Other particle
Net Force on Particle
Adsorption due to imbalanced force
Net force
Attraction
12C05.1 Adsorption and its types
84
Thermodynamics of Adsorption
12C05.1 Adsorption and its types
85
Thermodynamics of Adsorption
Change in heat of adsorption
ΔH
12C05.1 Adsorption and its types
86
Thermodynamics of Adsorption
Change in heat of adsorption
Change in entropy
ΔH
ΔS
12C05.1 Adsorption and its types
87
Thermodynamics of Adsorption
Change in heat of adsorption
Change in entropy
Change in Gibbs free energy
ΔH
ΔS
ΔG
12C05.1 Adsorption and its types
88
Change in heat of adsorption, ΔH
12C05.1 Adsorption and its types
89
Change in heat of adsorption, ΔH
A
B
AB
12C05.1 Adsorption and its types
90
Change in heat of adsorption, ΔH
Attraction
ΔH = - ve
A
B
AB
12C05.1 Adsorption and its types
91
Change in heat of adsorption, ΔH
Attraction
ΔH = - ve
A
B
AB
AB
A
B
12C05.1 Adsorption and its types
92
Change in heat of adsorption, ΔH
Separation
ΔH = + ve
Attraction
ΔH = - ve
A
B
AB
AB
A
B
12C05.1 Adsorption and its types
93
Change in heat of adsorption, ΔH
Separation
ΔH = + ve
Attraction
ΔH = - ve
A
B
AB
AB
A
B
Occurs in adsorption
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
94
Change in entropy, ΔS
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
95
Change in entropy, ΔS
Adsorbate
Adsorbent
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
96
Change in entropy, ΔS
Adsorbate
Adsorbent
Adsorbent
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
97
Change in entropy, ΔS
Randomness decrease
Adsorbate
Adsorbent
Adsorbent
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
98
Change in entropy, ΔS
Randomness decrease
ΔS = - ve
Adsorbate
Adsorbent
Adsorbent
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
99
Change in Gibbs Free Energy , ΔG
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
100
Change in Gibbs Free Energy , ΔG
Ice
Water
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
101
Change in Gibbs Free Energy , ΔG
Ice
Water
ΔG = - ve
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
102
Change in Gibbs Free Energy , ΔG
Ice
Water
Spontaneous process
ΔG = - ve
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
103
Change in Gibbs Free Energy , ΔG
Ice
Water
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
104
Change in Gibbs Free Energy , ΔG
Ice
Water
ΔG = + ve
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
105
Change in Gibbs Free Energy , ΔG
Ice
Water
Non - spontaneous process
ΔG = + ve
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
106
Change in Gibbs Free Energy , ΔG
Ice
Water
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
107
Change in Gibbs Free Energy , ΔG
Ice
Water
ΔG = 0
12C05.1 Adsorption and its type
12C05.1 Adsorption and its type
12C05.1 Adsorption and its types
108
Change in Gibbs Free Energy , ΔG
Ice
Water
Equilibrium
ΔG = 0
12C05.1 Adsorption and its types
109
Thermodynamics of adsorption
Change in heat of adsorption, ΔH
Change in entropy, ΔS
Change in Gibbs free energy, ΔG
Bond breaking
ΔH = +ve
Bond making
ΔH = -ve
Randomness increase, ΔS = +ve
Spontaneous
ΔG = -ve
Equilibrium
ΔG = 0
Randomness decrease, ΔS = -ve
Non - spontaneous
ΔG = +ve
12C05.1 Adsorption and its types
110
Relation between ∆H, ∆S and ∆G
12C05.1 Adsorption and its types
111
Relation between ∆H, ∆S and ∆G
∆G = ∆H - T ∆S
12C05.1 Adsorption and its types
112
Relation between ∆H, ∆S and ∆G
∆G = ∆H - T ∆S
- ve
- ve
For adsorption
12C05.1 Adsorption and its types
113
Relation between ∆H, ∆S and ∆G
∆G = ∆H - T ∆S
- ve
- ve
∆G = - ∆H + T ∆S
For adsorption
12C05.1 Adsorption and its types
114
∆G = ∆H - T∆S
∆G = −∆H +T∆S
12C05.1 Adsorption and its types
115
∆G = ∆H - T∆S
∆G = −∆H +T∆S
At low Temperature
∆H < T∆S
∆G = - ve
Spontaneous Process
12C05.1 Adsorption and its types
116
∆G = ∆H - T∆S
∆G = −∆H +T∆S
At low Temperature
∆H < T∆S
∆G = - ve
Spontaneous Process
If Temperature increases
∆H = T∆S
∆G = 0
Equilibrium Condition
12C05.1
CV 3
Types of Adsorption
12C05.1 Adsorption and its types
118
Types of Adsorption
12C05.1 Adsorption and its types
119
Types of Adsorption
Physical adsorption
Physisorption
12C05.1 Adsorption and its types
120
Types of Adsorption
Physical adsorption
Physisorption
Chemisorption
Chemicall adsorption
12C05.1 Adsorption and its types
121
Types of Adsorption
Adsorbate
Adsorbent
12C05.1 Adsorption and its types
122
Types of Adsorption
Adsorbate
Adsorbent
Weak van der Waals’ forces
12C05.1 Adsorption and its types
123
Types of Adsorption
Adsorbate
Adsorbent
Physisorption
Weak van der Waals’ forces
12C05.1 Adsorption and its types
124
Types of Adsorption
Adsorbate
Adsorbent
Physisorption
Weak van der Waals’ forces
Strong chemical bonds (Covalent or Ionic)
12C05.1 Adsorption and its types
125
Types of Adsorption
Adsorbate
Adsorbent
Physisorption
Chemisorption
Weak van der Waals’ forces
Strong chemical bonds (Covalent or Ionic)
12C05.1
CV 4
Characteristics of Physisorption
12C05.1 Adsorption and its types
127
Characteristics of Physisorption
1 - Lack of specificity
12C05.1 Adsorption and its types
128
Characteristics of Physisorption
1 - Lack of specificity
Adsorbent
Different gases
12C05.1 Adsorption and its types
129
Characteristics of Physisorption
1 - Lack of specificity
Adsorbent
Different gases
Universal weak van der Waals’ force
12C05.1 Adsorption and its types
130
Characteristics of Physisorption
1 - Lack of specificity
Adsorbent
Different gases
Adsorbent
Universal weak van der Waals’ force
12C05.1 Adsorption and its types
131
Characteristics of Physisorption
1 - Lack of specificity
Adsorbent
Different gases
All types of gases can adsorbed
Adsorbent
Universal weak van der Waals’ force
12C05.1 Adsorption and its types
132
Characteristics of Physisorption
2 - Nature of adsorbate
12C05.1 Adsorption and its types
133
Characteristics of Physisorption
Adsorbent
Adsorbent
2 - Nature of adsorbate
12C05.1 Adsorption and its types
134
Characteristics of Physisorption
Adsorbent
Adsorbent
Adsorbent
2 - Nature of adsorbate
12C05.1 Adsorption and its types
135
Characteristics of Physisorption
Adsorbent
Adsorbent
Adsorbent
Adsorbent
2 - Nature of adsorbate
12C05.1 Adsorption and its types
136
Characteristics of Physisorption
Adsorbent
Adsorbent
Adsorbent
Adsorbent
2 - Nature of adsorbate
High critical temperature
More adsorption
12C05.1 Adsorption and its types
ConcepTest
Ready for challenge
137
12C05.1 Adsorption and its types
Q. : What is the role of critical temperature, TC in adsorption of gases on solid surface?
12C05.1 Adsorption and its types
Pause the Video
(Time Duration : 02 Minutes)
Q. : What is the role of critical temperature, TC in adsorption of gases on solid surface?
12C05.1 Adsorption and its types
Q. : What is the role of critical temperature, TC in adsorption of gases on solid surface?
Sol. :
12C05.1 Adsorption and its types
Q. : What is the role of critical temperature, TC in adsorption of gases on solid surface?
Sol. : Critical temperature is one above which gases can't be liquefied, no matter
what the pressure is.
12C05.1 Adsorption and its types
Q. : What is the role of critical temperature, TC in adsorption of gases on solid surface?
Sol. : Critical temperature is one above which gases can't be liquefied, no matter
what the pressure is.
Critical temperature
Adsorption
12C05.1 Adsorption and its types
Q. : What is the role of critical temperature, TC in adsorption of gases on solid surface?
Sol. : Critical temperature is one above which gases can't be liquefied, no matter
what the pressure is.
Critical temperature
Adsorption
Gas | SO2 | NH3 | CO2 | H2 |
TC (K) | 430 | 406 | 304 | 33 |
Adsorption (ml) | 380 | 180 | 48 | 4.5 |
Adsorption of some gases per g of adsorbate at their critical temperature
12C05.1 Adsorption and its types
ConcepTest
Ready for challenge
144
12C05.1 Adsorption and its types
Q. : On the basis of TC given in the following table, arrange the given gases in the
increasing order of adsorption under identical conditions.
Gas | H2 | CO2 | CH4 | NH3 |
TC (K) | 33 | 304 | 190 | 406 |
12C05.1 Adsorption and its types
Pause the Video
(Time Duration : 02 Minutes)
Q. : On the basis of TC given in the following table, arrange the given gases in the
increasing order of adsorption under identical conditions.
Gas | H2 | CO2 | CH4 | NH3 |
TC (K) | 33 | 304 | 190 | 406 |
12C05.1 Adsorption and its types
Q. : On the basis of TC given in the following table, arrange the given gases in the
increasing order of adsorption under identical conditions.
Sol. :
Gas | H2 | CO2 | CH4 | NH3 |
TC (K) | 33 | 304 | 190 | 406 |
12C05.1 Adsorption and its types
Q. : On the basis of TC given in the following table, arrange the given gases in the
increasing order of adsorption under identical conditions.
Sol. :
Gas | H2 | CO2 | CH4 | NH3 |
TC (K) | 33 | 304 | 190 | 406 |
Intermolecular forces
Critical temp.
Adsorption
12C05.1 Adsorption and its types
Q. : On the basis of TC given in the following table, arrange the given gases in the
increasing order of adsorption under identical conditions.
Sol. :
Order of TC = H2 < CH4 < CO2 < NH3
Gas | H2 | CO2 | CH4 | NH3 |
TC (K) | 33 | 304 | 190 | 406 |
Intermolecular forces
Critical temp.
Adsorption
12C05.1 Adsorption and its types
Q. : On the basis of TC given in the following table, arrange the given gases in the
increasing order of adsorption under identical conditions.
Sol. :
Order of TC = H2 < CH4 < CO2 < NH3
Increasing order of Adsorption = H2 < CH4 < CO2 < NH3
Gas | H2 | CO2 | CH4 | NH3 |
TC (K) | 33 | 304 | 190 | 406 |
Intermolecular forces
Critical temp.
Adsorption
12C05.1 Adsorption and its types
151
3 - Reversible nature
Characteristics of Physisorption
12C05.1 Adsorption and its types
152
3 - Reversible nature
Characteristics of Physisorption
Adsorbent
Gas
12C05.1 Adsorption and its types
153
3 - Reversible nature
Characteristics of Physisorption
Adsorbent
Adsorbent
Gas
12C05.1 Adsorption and its types
154
3 - Reversible nature
Characteristics of Physisorption
Adsorbent
Adsorbent
Gas
weak van der Waals’ force
12C05.1 Adsorption and its types
155
3 - Reversible nature
Characteristics of Physisorption
Adsorbent
Adsorbent
Adsorbent
Gas
weak van der Waals’ force
Easy desorption
12C05.1 Adsorption and its types
156
4 - Change with Pressure
Characteristics of Physisorption
12C05.1 Adsorption and its types
157
Pressure
Characteristics of Physisorption
Adsorption
4 - Change with Pressure
12C05.1 Adsorption and its types
158
Pressure
Characteristics of Physisorption
Piston
Gas molecules
Adsorbent
Adsorption
4 - Change with Pressure
12C05.1 Adsorption and its types
159
Pressure
Characteristics of Physisorption
Piston
Gas molecules
Adsorbent
Less adsorption
Low pressure
Adsorption
4 - Change with Pressure
12C05.1 Adsorption and its types
160
Pressure
Characteristics of Physisorption
Piston
Gas molecules
Adsorbent
Less adsorption
More adsorption
Low pressure
High pressure
Adsorption
4 - Change with Pressure
12C05.1 Adsorption and its types
ConcepTest
Ready for challenge
161
12C05.1 Adsorption and its types
Q. : Why does physical adsorption increase with pressure?
12C05.1 Adsorption and its types
Pause the Video
(Time Duration : 01 Minutes)
Q. : Why does physical adsorption increase with pressure?
12C05.1 Adsorption and its types
Q. : Why does physical adsorption increase with pressure?
Sol. :
12C05.1 Adsorption and its types
Q. : Why does physical adsorption increase with pressure?
Sol. : According to the Le–Chatelier’s principle, If we increase pressure of the system
at equilibrium state, the equilibrium will shift towards lesser number of gaseous
molecules to reduce the pressure of the system
12C05.1 Adsorption and its types
Q. : Why does physical adsorption increase with pressure?
Sol. : According to the Le–Chatelier’s principle, If we increase pressure of the system
at equilibrium state, the equilibrium will shift towards lesser number of gaseous
molecules to reduce the pressure of the system
12C05.1 Adsorption and its types
Q. : Why does physical adsorption increase with pressure?
Sol. : According to the Le–Chatelier’s principle, If we increase pressure of the system
at equilibrium state, the equilibrium will shift towards lesser number of gaseous
molecules to reduce the pressure of the system
Equilibrium state
12C05.1 Adsorption and its types
Q. : Why does physical adsorption increase with pressure?
Sol. : According to the Le–Chatelier’s principle, If we increase pressure of the system
at equilibrium state, the equilibrium will shift towards lesser number of gaseous
molecules to reduce the pressure of the system
Equilibrium state
At low P
12C05.1 Adsorption and its types
Q. : Why does physical adsorption increase with pressure?
Sol. : According to the Le–Chatelier’s principle, If we increase pressure of the system
at equilibrium state, the equilibrium will shift towards lesser number of gaseous
molecules to reduce the pressure of the system
Equilibrium state
At low P
At high P
12C05.1 Adsorption and its types
170
5 - Change with Temperature
Characteristics of Physisorption
12C05.1 Adsorption and its types
171
Adsorption is an exothermic process
Characteristics of Physisorption
5 - Change with Temperature
12C05.1 Adsorption and its types
172
Adsorption
Adsorption is an exothermic process
Temp.
Characteristics of Physisorption
5 - Change with Temperature
12C05.1 Adsorption and its types
173
Adsorption
Adsorption is an exothermic process
Temp.
Adsorbent
More adsorption
Characteristics of Physisorption
5 - Change with Temperature
12C05.1 Adsorption and its types
174
Adsorption
Adsorption is an exothermic process
Temp.
Adsorbent
Adsorbent
More adsorption
Less adsorption
Characteristics of Physisorption
5 - Change with Temperature
12C05.1 Adsorption and its types
175
Characteristics of Physisorption
5 - Change with Temperature
12C05.1 Adsorption and its types
176
Characteristics of Physisorption
Amount of gas adsorbed
Temperature
5 - Change with Temperature
12C05.1 Adsorption and its types
177
Characteristics of Physisorption
Amount of gas adsorbed
Temperature
5 - Change with Temperature
12C05.1 Adsorption and its types
178
Characteristics of Physisorption
Amount of gas adsorbed
Temperature
High adsorption
Low temp.
5 - Change with Temperature
12C05.1 Adsorption and its types
179
Characteristics of Physisorption
Amount of gas adsorbed
Temperature
High adsorption
Low adsorption
High temp.
Low temp.
5 - Change with Temperature
12C05.1 Adsorption and its types
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12C05.1 Adsorption and its types
Q. : Why does physisorption decrease with the increase of temperature?
12C05.1 Adsorption and its types
Pause the Video
(Time Duration : 01 Minutes)
Q. : Why does physisorption decrease with the increase of temperature?
12C05.1 Adsorption and its types
Q. : Why does physisorption decrease with the increase of temperature?
Sol. :
12C05.1 Adsorption and its types
Q. : Why does physisorption decrease with the increase of temperature?
Sol. :
Adsorption is an exothermic process
ΔH = -ve
12C05.1 Adsorption and its types
Q. : Why does physisorption decrease with the increase of temperature?
Sol. :
Adsorption is an exothermic process
ΔH = -ve
From Le–Chatelier’s principle -
For an exothermic process, an increase in temperature shifts the process in backward direction - adsorption will decrease
12C05.1 Adsorption and its types
Q. : Why does physisorption decrease with the increase of temperature?
Sol. :
Adsorption is an exothermic process
ΔH = -ve
From Le–Chatelier’s principle -
For an exothermic process, an increase in temperature shifts the process in backward direction - adsorption will decrease
12C05.1 Adsorption and its types
187
6 - Enthalpy of Adsorption
Characteristics of Physisorption
12C05.1 Adsorption and its types
188
6 - Enthalpy of Adsorption
Characteristics of Physisorption
Adsorbent
Adsorbate
12C05.1 Adsorption and its types
189
6 - Enthalpy of Adsorption
Characteristics of Physisorption
Adsorbent
Weak van der Waals’ force
Adsorbate
12C05.1 Adsorption and its types
190
6 - Enthalpy of Adsorption
Characteristics of Physisorption
Adsorbent
Weak van der Waals’ force
Release less energy during adsorption
Only 20 to 40 kj mol-1
Adsorbate
12C05.1 Adsorption and its types
191
7 - Surface area of adsorbent
Characteristics of Physisorption
12C05.1 Adsorption and its types
192
7 - Surface area of adsorbent
Characteristics of Physisorption
Surface area of adsorbent Adsorption
12C05.1 Adsorption and its types
193
7 - Surface area of adsorbent
Characteristics of Physisorption
Surface area of adsorbent Adsorption
Dividing adsorbent
12C05.1 Adsorption and its types
194
7 - Surface area of adsorbent
Characteristics of Physisorption
Surface area of adsorbent Adsorption
Less surface area
Less adsorption
More surface area
More adsorption
Dividing adsorbent
12C05.1 Adsorption and its types
195
7 - Surface area of adsorbent
Characteristics of Physisorption
Surface area of adsorbent Adsorption
Less surface area
Less adsorption
More surface area
More adsorption
New surface for more adsorption
Dividing adsorbent
12C05.1 Adsorption and its types
196
8 - Activation energy
Characteristics of Physisorption
12C05.1 Adsorption and its types
197
8 - Activation energy
Characteristics of Physisorption
Weak van der Waal force is present b/w adsorbate and adsorbent
12C05.1 Adsorption and its types
198
8 - Activation energy
Characteristics of Physisorption
Weak van der Waal force is present b/w adsorbate and adsorbent
No appreciable activation energy is needed
12C05.1 Adsorption and its types
199
9 - Multilayer Adsorption
Characteristics of Physisorption
12C05.1 Adsorption and its types
200
9 - Multilayer Adsorption
Characteristics of Physisorption
Adsorbent
Adsorbate
Adsorbent
Multilayer Adsorption
1st Layer
2nd Layer
12C05.1 Adsorption and its types
201
9 - Multilayer Adsorption
Characteristics of Physisorption
Adsorbent
Adsorbate
Multilayer Adsorption
Due to Lack of specificity
Molecule can adsorbed on molecule
Adsorbent
1st Layer
2nd Layer
12C05.1
CV 5
Characteristics of Chemisorption
12C05.1 Adsorption and its types
203
1 - High Specificity
Characteristics of Chemisorption
12C05.1 Adsorption and its types
204
1 - High Specificity
Characteristics of Chemisorption
Adsorbent
Different gases
12C05.1 Adsorption and its types
205
1 - High Specificity
Characteristics of Chemisorption
Adsorbent
Different gases
Strongly Attracted towards adsorbent
12C05.1 Adsorption and its types
206
1 - High Specificity
Characteristics of Chemisorption
Adsorbent
Adsorbent
Different gases
Some specific gases can only be adsorbed
Strongly Attracted towards adsorbent
12C05.1 Adsorption and its types
207
2 - Irreversibility
Characteristics of Chemisorption
12C05.1 Adsorption and its types
208
2 - Irreversibility
Characteristics of Chemisorption
12C05.1 Adsorption and its types
209
2 - Irreversibility
Characteristics of Chemisorption
Strong chemical bond between adsorbate and adsorbent
12C05.1 Adsorption and its types
210
2 - Irreversibility
Difficult to separate adsorbent and adsorbate
Characteristics of Chemisorption
Strong chemical bond between adsorbate and adsorbent
12C05.1 Adsorption and its types
211
2 - Irreversibility
Difficult to separate adsorbent and adsorbate
Characteristics of Chemisorption
Strong chemical bond between adsorbate and adsorbent
Chemisorption is Irreversible
12C05.1 Adsorption and its types
212
3 - Change with Pressure
Characteristics of Chemisorption
12C05.1 Adsorption and its types
213
Pressure Adsorption
3 - Change with Pressure
Characteristics of Chemisorption
Like physisorption
12C05.1 Adsorption and its types
214
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
215
Adsorbent
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
216
Adsorbent
Adsorbent
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
217
Adsorbent
Adsorbent
Adsorbent
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
218
Amount of gas adsorbed
Temperature
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
219
Amount of gas adsorbed
Temperature
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
220
Amount of gas adsorbed
Temperature
Low tem.
Low adsorption
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
221
Amount of gas adsorbed
Temperature
Low tem.
Low adsorption
Temp. increases
Adsorption increases
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
222
Amount of gas adsorbed
Temperature
Low tem.
Low adsorption
High temp.
low adsorption
Temp. increases
Adsorption increases
4 - Change with Temperature
Characteristics of Chemisorption
12C05.1 Adsorption and its types
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12C05.1 Adsorption and its types
Q. : How does temperature change the chemical adsorption?
12C05.1 Adsorption and its types
Pause the Video
(Time Duration : 01 Minutes)
Q. : How does temperature change the chemical adsorption?
12C05.1 Adsorption and its types
Q. : How does temperature change the chemical adsorption?
Sol. :
12C05.1 Adsorption and its types
Q. : How does temperature change the chemical adsorption?
Sol. :
Amount of gas adsorbed
Temperature
12C05.1 Adsorption and its types
Q. : How does temperature change the chemical adsorption?
Sol. :
Amount of gas adsorbed
Temperature
Initially adsorption increases
Temperature gives heat for reaction
12C05.1 Adsorption and its types
Q. : How does temperature change the chemical adsorption?
Sol. :
Amount of gas adsorbed
Temperature
temperature gives heat for reaction
Initially adsorption increases
Due to exothermic nature excess heat breaks the bonds b/w adsorbate and adsorbent
12C05.1 Adsorption and its types
230
5 - Enthalpy of Adsorption
Characteristics of Chemisorption
12C05.1 Adsorption and its types
231
5 - Enthalpy of Adsorption
Adsorbent
Adsorbate
Characteristics of Chemisorption
Strong chemical bonds
12C05.1 Adsorption and its types
232
5 - Enthalpy of Adsorption
Adsorbent
Adsorbate
Characteristics of Chemisorption
Strong chemical bonds
Release high energy during adsorption
80 – 240 kJ mol-1
12C05.1 Adsorption and its types
233
6 - Surface area of adsorbent
Characteristics of Chemisorption
12C05.1 Adsorption and its types
234
6 - Surface area of adsorbent
Surface area of adsorbent Adsorption
Characteristics of Chemisorption
12C05.1 Adsorption and its types
235
7 - Activation energy
Characteristics of physisorption
Characteristics of Chemisorption
12C05.1 Adsorption and its types
236
7 - Activation energy
Characteristics of physisorption
Strong chemical bonds are present b/w adsorbate and adsorbent
Characteristics of Chemisorption
12C05.1 Adsorption and its types
237
7 - Activation energy
Characteristics of physisorption
Strong chemical bonds are present b/w adsorbate and adsorbent
Sometimes high activation energy is needed
Characteristics of Chemisorption
12C05.1 Adsorption and its types
238
Characteristics of Chemisorption
8 - Unimolecular layer Adsorption
12C05.1 Adsorption and its types
239
Characteristics of Chemisorption
8 - Unimolecular layer Adsorption
Chemical bond will be formed between adsorbent and adsorbate only
12C05.1 Adsorption and its types
240
8 - Unimolecular layer Adsorption
Characteristics of Chemisorption
Chemical bond will be formed between adsorbent and adsorbate only
Adsorbate
Adsorbent
Unimolecular layer
12C05.1 Adsorption and its types
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12C05.1 Adsorption and its types
Q. : What are the major differences between physisorption and chemisorption?
12C05.1 Adsorption and its types
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Q. : What are the major differences between physisorption and chemisorption?
12C05.1 Adsorption and its types
Q. : What are the major differences between physisorption and chemisorption?
Sol. :
12C05.1 Adsorption and its types
Q. : What are the major differences between physisorption and chemisorption?
Sol. :
Physisorption | Chemisorption |
Van der Waals’ forces | Chemical bonds |
Not specific nature | Highly specific |
Reversible nature | irreversible nature |
Low enthalpy of adsorption | High enthalpy of adsorption |
Low activation energy | High activation energy |
Multimolecular layers | Unimolecular layer |
12C05.1 Adsorption and its types
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12C05.1 Adsorption and its types
Q. : What are the major factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
247
12C05.1 Adsorption and its types
Q. : What are the major factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Pause the Video
(Time Duration : 02 Minutes)
248
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
249
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
250
Extent of adsorption depends on nature of adsorbent and adsorbate
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
251
Surface area of the adsorbent Adsorption
Extent of adsorption depends on nature of adsorbent and adsorbate
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
252
Surface area of the adsorbent Adsorption
Pressure of gas Adsorption
Extent of adsorption depends on nature of adsorbent and adsorbate
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
253
Extent of adsorption depends on nature of adsorbent and adsorbate
Surface area of the adsorbent Adsorption
Pressure of gas Adsorption
Temperature
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
254
Extent of adsorption depends on nature of adsorbent and adsorbate
Surface area of the adsorbent Adsorption
Pressure of gas Adsorption
Temperature
Physisorption
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
255
Extent of adsorption depends on nature of adsorbent and adsorbate
Surface area of the adsorbent Adsorption
Pressure of gas Adsorption
Temperature
Physisorption
Chemisorption, initially
12C05.1 Adsorption and its types
Question : What are the factors which influence the adsorption of a gas on a solid?
(NCERT Exercise Question 5.4, pg no. 148)
Sol. :
256
Extent of adsorption depends on nature of adsorbent and adsorbate
Surface area of the adsorbent Adsorption
Pressure of gas Adsorption
Temperature
Physisorption
Chemisorption, initially
At high Temp.
12C05.1 Adsorption and its types
: Reference Questions :
Intext Questions : 5.1 and 5.3 (NCERT page no. 129)
Exercise Questions : 5.1, 5.2, 5.3, 5.6, 5.8, 5.10 ( NCERT page no. 148)
Workbook Questions : 2, 3, 9,
257
12C05.2
Adsorption Isotherm
12C05.2 Adsorption Isotherm
Learning Objectives
Adsorption Isotherm
Freundlich adsorption Isotherm
Adsorption from Solution Phase
Applications of Adsorption
259
12C05.2
CV 1
Adsorption Isotherm
12C05.2 Adsorption Isotherm
261
Adsorption Isotherm
12C05.2 Adsorption Isotherm
262
Adsorption Isotherm
12C05.2 Adsorption Isotherm
263
Amount of gas adsorbed
Adsorption Isotherm
12C05.2 Adsorption Isotherm
264
Amount of gas adsorbed
Pressure
Adsorption Isotherm
12C05.2 Adsorption Isotherm
265
Amount of gas adsorbed
Pressure
At constant temperature
Adsorption Isotherm
12C05.2 Adsorption Isotherm
266
Adsorption Isotherm
Amount of gas adsorbed
Pressure
At constant temperature
Explain by Freundlich
12C05.2 Adsorption Isotherm
267
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
268
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
269
Freundlich adsorption isotherm
An equation to relate amount of gas adsorbed with pressure at constant temperature
12C05.2 Adsorption Isotherm
270
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
271
x/m = Extent of adsorption
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
272
x/m = Extent of adsorption
x = Mass of gas adsorbed
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
273
x/m = Extent of adsorption
x = Mass of gas adsorbed
m = Mass of absorbent
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
274
x/m = Extent of adsorption
x = Mass of gas adsorbed
m = Mass of adsorbent
p = Pressure
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
275
x/m = Extent of adsorption
x = Mass of gas adsorbed
m = Mass of adsorbent
p = Pressure
k = Constant
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
276
x/m = Extent of adsorption
x = Mass of gas adsorbed
m = Mass of adsorbent
p = Pressure
k = Constant
n = Constant
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
277
x/m = Extent of adsorption
x = Mass of gas adsorbed
m = Mass of adsorbent
p = Pressure
k = Constant
n = Constant
Depend on nature of gas, adsorbent and temperature
Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
278
Graphical representation of Freundlich adsorption isotherm
At Constant Temperature
12C05.2 Adsorption Isotherm
279
Graphical representation of Freundlich adsorption isotherm
At Constant Temperature
12C05.2 Adsorption Isotherm
280
Graphical representation of Freundlich adsorption isotherm
There are three possible cases
At Constant Temperature
12C05.2 Adsorption Isotherm
281
Cases of Freundlich adsorption isotherm
At low pressure
12C05.2 Adsorption Isotherm
282
Cases of Freundlich adsorption isotherm
At low pressure
At high pressure
12C05.2 Adsorption Isotherm
283
Cases of Freundlich adsorption isotherm
At moderate pressure
At low pressure
At high pressure
12C05.2 Adsorption Isotherm
284
Case - 1
12C05.2 Adsorption Isotherm
285
Case - 1
12C05.2 Adsorption Isotherm
286
Case - 1
12C05.2 Adsorption Isotherm
287
Case - 1
12C05.2 Adsorption Isotherm
288
Case - 1
12C05.2 Adsorption Isotherm
289
Case - 1
12C05.2 Adsorption Isotherm
290
Case - 2
12C05.2 Adsorption Isotherm
291
Case - 2
12C05.2 Adsorption Isotherm
292
Case - 2
12C05.2 Adsorption Isotherm
293
Case - 2
12C05.2 Adsorption Isotherm
294
Case - 2
12C05.2 Adsorption Isotherm
295
Case - 2
PS
12C05.2 Adsorption Isotherm
296
Case - 3
12C05.2 Adsorption Isotherm
297
Case - 3
12C05.2 Adsorption Isotherm
298
Case - 3
12C05.2 Adsorption Isotherm
299
Case - 3
12C05.2 Adsorption Isotherm
300
Case - 3
12C05.2 Adsorption Isotherm
301
Validity of Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
302
Validity of Freundlich adsorption isotherm
Freundlich adsorption isotherm equation
12C05.2 Adsorption Isotherm
303
Validity of Freundlich adsorption isotherm
Freundlich adsorption isotherm equation
Taking logarithm
12C05.2 Adsorption Isotherm
304
Validity of Freundlich adsorption isotherm
Freundlich adsorption isotherm equation
Taking logarithm
12C05.2 Adsorption Isotherm
305
Validity of Freundlich adsorption isotherm
Freundlich adsorption isotherm equation
Taking logarithm
12C05.2 Adsorption Isotherm
306
Validity of Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
307
Validity of Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
308
Validity of Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
309
Validity of Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
310
Validity of Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
311
Slope = m =
Validity of Freundlich adsorption isotherm
Intercept = c = log k
Comparing with
12C05.2 Adsorption Isotherm
312
Comparing log form of Freundlich equation with the equation of straight line
vs
12C05.2 Adsorption Isotherm
313
Limitations of Freundlich adsorption isotherm
12C05.2 Adsorption Isotherm
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12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
12C05.2 Adsorption Isotherm
Pause the Video
(Time Duration : 02 Minutes)
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
Sol. : Given - curve between log x/m and log p is straight line
12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
Sol. : Given - curve between log x/m and log p is straight line
Slope =
12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
Sol. : Given - curve between log x/m and log p is straight line
Slope =
12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
Sol. : Given - curve between log x/m and log p is straight line
Slope =
Intercept =
12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
Sol. : Given - curve between log x/m and log p is straight line
Slope =
Intercept =
12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
Sol. : Given - curve between log x/m and log p is straight line
Slope =
Intercept =
12C05.2 Adsorption Isotherm
Q. : A curve between log x/m and log p is found to be straight line with a slope of 45° and intercept 0.3010. Calculate the amount of gas adsorbed at 0.2 atm pressure.
Sol. : Given - curve between log x/m and log p is straight line
Slope =
Intercept =
12C05.2
CV 2
Adsorption from Solution Phase
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
325
Adsorption from Solution Phase
Solids can adsorb solutes from solutions
Iodine solution
Iodine solution with charcoal
Colourless iodine solution
Adding charcoal
Colour adsorbed by charcoal
12C05.1 Adsorption and its type
326
Adsorption from Solution Phase
Litmus solution
Colourless solution
Animal charcoal
Colouring agent of litmus solution is adsorbed by animal charcoal
12C05.2 Adsorption Isotherm
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12C05.2 Adsorption Isotherm
Q. : Why does White precipitate of Mg(OH)2 turn blue in magneson reagent?
12C05.2 Adsorption Isotherm
Pause the Video
(Time Duration : 02 Minutes)
Q. : Why does White precipitate of Mg(OH)2 turn blue in magneson reagent?
12C05.2 Adsorption Isotherm
Q. : Why does White precipitate of Mg(OH)2 turn blue in magneson reagent?
Sol. : Blue coloured Magneson gets adsorbed on the surface of white ppt of Mg(OH)2
White precipitate of Mg(OH)2
Magneson reagent
Blue precipitate of Mg(OH)2
12C05.1 Adsorption and its types
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12C05.1 Adsorption and its types
Question : Why does a blue colour of methylene blue solution fade on adding small
amount of activated charcoal ?
12C05.1 Adsorption and its types
Pause the Video
(Time Duration : 02 Minutes)
Question : Why does a blue colour of methylene blue solution fade on adding small
amount of activated charcoal ?
12C05.1 Adsorption and its types
Question : Why does a blue colour of methylene blue solution fade on adding small
amount of activated charcoal ?
Solution : The colouring agent of methylene blue is adsorbed by activated charcoal.
12C05.1 Adsorption and its types
Question : Why does a blue colour of methylene blue solution fade on adding small
amount of activated charcoal ?
Solution : The colouring agent of methylene blue is adsorbed by activated charcoal.
Methylene blue
Blue colour faded by charcoal
Activated charcoal
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
336
Adsorption from Solution Phase
Some important observations for adsorption from solution phase
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
337
Adsorption from Solution Phase
Mechanism
Precise mechanism
Freundlich equation approximately describes the behaviour of
adsorption from solution
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
338
Adsorption from Solution Phase
Describes with the help of Freundlich equation
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
339
Adsorption from Solution Phase
To calculate the value of constants k and n
12C05.2
CV 3
Applications of Adsorption
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
341
Applications of adsorption
1 - Production of high vacuum
Remaining traces of air can be adsorbed by charcoal from a vessel evacuated by a vacuum pump to provide a very high vacuum
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
342
Applications of adsorption
1 - Production of high vacuum
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
343
Applications of adsorption
1 - Production of high vacuum
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
344
Applications of adsorption
2 - Gas masks
Gas mask loaded with activated charcoal or any other safe adsorbents is usually used for breathing in coal mines to adsorb poisonous gases
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
345
Applications of adsorption
3 - Control of humidity
Silica and aluminium gels can adsorb moisture very effectively
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
346
Applications of adsorption
4 - Removal of colouring matter
Animal charcoal
removes colours of solutions by adsorbing coloured impurities
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
347
Applications of adsorption
5 - Heterogeneous catalysis
Adsorption of reactants on the solid
surface of the catalysts increases the rate of reaction
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
348
Applications of adsorption
6 - Separation of inert gases
A mixture of noble gases can be separated by adsorption on coconut charcoal at different temperatures
Difference in degree of adsorption of gases
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
349
Applications of adsorption
7 - In curing diseases
Adsorption of drug on the germs can kill them or stop their growth
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
350
Applications of adsorption
8 - Adsorption indicators
Surfaces of certain precipitates such as silver halides have the property of adsorbing some indicator dyes like eosin, fluorescein, etc.
Characteristic colour indicated the end point
12C05.1 Adsorption and its type
: Reference Questions :
Exercise Questions : 5.5 ( NCERT page no. 148)
Workbook Questions : 6, 10
351
PSV
12C05.1 Adsorption and its type
353
CT
12C05.3
Catalysis
CV 1
Catalysis and its types
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Catalysis
2KClO3
653-873 K
2KCl + 3O2
2KClO3
473-633 K
2KCl + 3O2
MnO2
Slow
Comparatively Fast
Mass and composition remains unchanged
Can alter rate of reaction
Catalyst
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Substances, which accelerate the rate of a chemical reaction and themselves remain chemically and quantitatively unchanged after the reaction, are known as catalysts, and the phenomenon is known as catalysis
Catalysis
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Promoters and poisons
N2(g) + 3H2(g)
2NH3(g)
Fe
Mo
N2(g) + 3H2(g)
2NH3(g)
Fe
H2S
Enhance the activity of catalyst
Decrease the activity of catalyst
Promoters
Poisons
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Types of Catalysis
Homogeneous
Heterogeneous
Reactants products and the catalyst are in the same phase
Reactants products and the catalyst are in different phase
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Homogeneous Catalysis
2SO2(g) + O2(g)
2SO2(g)
NO(g)
CH3COOCH3(l) + H2O(l)
CH3COOH(aq) + CH3OH(aq)
HCI(l)
C6H12O6 (aq) + C6H12O6(aq)
C12H22O11 (aq) + H2O(l)
H2SO4(l)
Lead chamber process
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Heterogeneous Catalysis
2SO2(g) + O2(g)
2SO2(g)
Pt(S)
4NO(g) + 6H O(g)
4NH (g) + 5O (g)
Ni(S)
Haber’s process
N2(g) + 3H2(g)
2NH3(g)
Fe(S)
Ostwald’s process
CV 2
Adsorption Theory of Heterogeneous Catalysis
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Adsorption Theory of Heterogeneous Catalysis
Explains the mechanism of heterogeneous catalysis
Modern adsorption theory of catalysis
Old adsorption theory
of catalysis
Intermediate compound formation theory
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Old Adsorption Theory of Catalysis
Reactants in gaseous state or in solutions, are adsorbed on the surface of the solid catalyst
Increase in concentration of reactants on the surface increases rate of reaction
Adsorption being an exothermic process, the heat of adsorption is utilised in
enhancing the rate of the reaction
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Intermediate compound formation theory
Explains the catalytic action of the catalyst
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It is the combination
Modern adsorption theory of catalysis
Modern adsorption theory of catalysis
Old adsorption theory
of catalysis
The catalytic activity is localised on the surface of the catalyst
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Modern adsorption theory of catalysis
Diffusion of reactants to the surface of the catalyst
Adsorption of reactant molecules on the surface of the catalyst
Desorption of reaction products from the catalyst surface
Formation of an intermediate on the catalyst’s surface due to chemical reaction
Diffusion of reaction products away from the catalyst’s surface
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A
B
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A
B
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A
B
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A
B
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A
B
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A
B
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Modern adsorption theory of catalysis
Limitations
Advantages
Explains -
does not explain -
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Important features of solid catalysts
Selectivity
Activity
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Important features of solid catalysts
Selectivity
Activity
CO(g) + 3H2(g)
CH4(g) + H2O(g)
Ni
CO(g) + 2H2(g)
CH3OH(aq)
Cu/ZnO-Cr2O3
CV 2
Shape Selective Catalysis
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Shape Selective Catalysis
A catalytic reaction that depends upon -
Pore structure of the catalyst
Size of the reactant and product molecules
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Shape Selective Catalysis
A catalytic reaction that depends upon -
Pore structure of the catalyst
Size of the reactant and product molecules
Zeolites are good shape-selective catalysts
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Zeolites
What are the Zeolites ?
How they act as Shape Selective Catalysts ?
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What are the Zeolites ?
They are microporous aluminosilicates
3-D network of silicates in which some silicon atoms are replaced by aluminium atoms giving Al–O–Si framework
Reactions taking place in zeolites depend upon the size and shape of reactant and product molecules as well as upon pores and cavities of the zeolites
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How they act as Shape Selective Catalysts ?
Zeolites are good shape selective catalysts
because of their honeycomb-like structures
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Uses of Zeolites
It converts alcohols directly into gasoline (petrol) by dehydrating them
Zeolites are widely used as catalysts in petrochemical industries for cracking of hydrocarbons
An important zeolite catalyst used in the petroleum industry is ZSM-5
CV 2
Enzyme Catalysis
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Enzyme Catalysis
Where they act as catalyst ❓
When reactions are catalysed by enzymes
What are enzymes❓
How they act as catalyst ❓
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What are Enzyme ❓
Enzymes are complex nitrogenous organic compounds which are produced by living plants and animals
They are actually protein molecules of high molecular mass
They are very effective catalysts as they catalyse numerous reactions, especially those connected with natural processes
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Where they act as catalyst ❓
Enzymes are, thus, termed as biochemical catalysts and the phenomenon is known as biochemical catalysis
Many reactions occur in bodies of animals and plants to maintain life process are catalysed by enzymes
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Homogeneous Catalysis
1 - Inversion of cane sugar
2 - Conversion of glucose into ethyl alcohol
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Homogeneous Catalysis
3 - Conversion of starch into maltose
4 - Conversion of maltose into glucose
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Homogeneous Catalysis
5 - Decomposition of urea
Curd
Milk
Lacto Bacilli
6 - Conversion of milk into curd
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Homogeneous Catalysis
Peptides
Proteins
Pepsin
Amino acids
Proteins
Trypsin
7 - In stomach
8 - in intestine
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Characteristics of enzyme catalysis
High efficiency
pH dependent
Highly specific
Affected by activators and co-enzymes
Temp. dependent
Affected by inhibitors and poisons
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Characteristics of enzyme catalysis
1- High efficiency - One molecule of an enzyme may transform one million molecules of the reactant per minute
2 - Highly specific nature - Each enzyme is specific for a given reaction
For example - the enzyme urease catalyses the hydrolysis of urea only. It does not catalyse hydrolysis of any other amide
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Characteristics of enzyme catalysis
3 - Optimum temperature - Rate of an enzyme reaction becomes maximum at definite temperature, called the optimum temperature.
Optimum temperature range for enzymatic activity is 298-310K. Human body temperature being 310 K is suited for enzyme-catalysed reactions
Temp. other than optimum temperature, will decreases the enzyme activity
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Characteristics of enzyme catalysis
4 - Optimum pH - Rate of an enzyme-catalysed
reaction is maximum at a particular pH called optimum pH
Optimum pH is between pH values 5-7
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Characteristics of enzyme catalysis
5 - Effect of activators and co-enzymes - The enzymatic activity is increased in the presence of certain substances, known as co-enzymes
It has been observed that when a small non-protein (vitamin) is present along with an enzyme, the catalytic activity is enhanced considerably
Activators are generally metal ions such as Na+, Mn2+, Co2+, Cu2+,
etc. These metal ions, when weakly bonded to enzyme molecules,
increase their catalytic activity. Amylase in presence of sodium
chloride i.e., Na+ ions are catalytically very active
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Characteristics of enzyme catalysis
6 - Effect of inhibitors and poisons - Like ordinary catalysts, enzymes
are also inhibited or poisoned by the presence of certain substances.
The inhibitors or poisons interact with the active functional groups
on the enzyme surface and often reduce or completely destroy the
catalytic activity of the enzymes. The use of many drugs is related
to their action as enzyme inhibitors in the body
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Characteristics of enzyme catalysis
Mechanism of enzyme catalysis - There are a number of cavities present on the surface of colloidal particles of enzymes. These cavities are of characteristic shape and possess active groups such as -NH2, -COOH, -SH, -OH, etc. These are actually the active centres on the surface of enzyme particles. The molecules of the reactant (substrate), which have complementary shape, fit into these cavities just like a key fits into a lock. On account of the presence of active groups, an activated complex is formed which then decomposes to yield the products. Thus, the enzyme-catalysed reactions may be considered to proceed in two steps.
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Characteristics of enzyme catalysis
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Characteristics of enzyme catalysis
Step 1: Binding of enzyme to substrate to form an activated complex.
E + S → ES≠
Step 2: Decomposition of the activated complex to form product.
ES≠ →E +
12C05.4
Colloids
12C05.2 Adsorption Isotherm and Freundlich adsorption Isotherm
410
CV 1
Colloids
12C05.4 Colloids
412
FC
On the basis of study of diffusion of solutions through an animal membrane, Thomas Graham divided the various solute-solvent systems in two categorie
12C05.4 Colloids
413
FC
On the basis of study of diffusion of solutions through an animal membrane, Thomas Graham divided the various solute-solvent systems in two categorie
Crystalloids
Colloids
12C05.4 Colloids
414
FC
On the basis of study of diffusion of solutions through an animal membrane, Thomas Graham divided the various solute-solvent systems in two categorie
Crystalloids
Colloids
Def. Some crystalline substances whose solutions were able to pass through an animal membrane
E.g. Aq. solution of sugar, urea, sodium chloride
12C05.4 Colloids
415
FC
On the basis of study of diffusion of solutions through an animal membrane, Thomas Graham divided the various solute-solvent systems in two categorie
Crystalloids
Colloids
Def. Some crystalline substances whose solutions were able to pass through an animal membrane
E.g. Aq. solution of sugar, urea, sodium chloride
Def. Some amorphous substances whose solutions were unable to pass through the membrane
E.g. Solutions of glue, gelatin, gum Arabic etc
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416
FC
On the basis of study of diffusion of solutions through an animal membrane, Thomas Graham divided the various solute-solvent systems in two categorie
Crystalloids
Colloids
Def. Some crystalline substances whose solutions were able to pass through an animal membrane
E.g. Aq. solution of sugar, urea, sodium chloride
Def. Some amorphous substances whose solutions were unable to pass through the membrane
E.g. Solutions of glue, gelatin, gum Arabic etc
Division was not successful as certain substances can act as crystalloids and colloids
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417
FC
Division of solute-solvent systems
12C05.4 Colloids
418
FC
Division of solute-solvent systems
On the basis of the size of solute particles
12C05.4 Colloids
419
FC
Division of solute-solvent systems
True solution
On the basis of the size of solute particles
12C05.4 Colloids
420
FC
Division of solute-solvent systems
True solution
Suspension
On the basis of the size of solute particles
12C05.4 Colloids
421
Division of solute-solvent systems
True solution
Suspension
Colloids
On the basis of the size of solute particles
12C05.4 Colloids
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True Solution
12C05.4 Colloids
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Suspension
12C05.4 Colloids
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FC
Colloids
12C05.4 Colloids
425
FC
Colloids
Def. Colloid is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium
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FC
Colloids
On the basis of the size of the solute particles, colloids are exist between suspensions and solutions
Def. Colloid is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium
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427
Properties of Colloids
PSV
CT
CV 2
Classification of Colloids
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FC
Classification of Colloids
Colloids are classified on the basis of the following criteria -
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FC
Classification of Colloids
1 - Physical state of dispersed phase and dispersion medium
Colloids are classified on the basis of the following criteria -
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FC
Classification of Colloids
1 - Physical state of dispersed phase and dispersion medium
Colloids are classified on the basis of the following criteria -
2 - Nature of interaction between dispersed phase and dispersion
medium
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FC
Classification of Colloids
1 - Physical state of dispersed phase and dispersion medium
3 - Type of particles of the dispersed phase
Colloids are classified on the basis of the following criteria -
2 - Nature of interaction between dispersed phase and dispersion
medium
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435
FC
Depending upon the physical states of dispersed phase and dispersion
Medium, there are eight types of colloidal systems
Classification based on physical state of dispersed phase and dispersion medium
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Table : Types of colloids
Classification based on physical state of dispersed phase and dispersion medium
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Classification based on physical state of dispersed phase and dispersion medium
Some important points
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Classification based on physical state of dispersed phase and dispersion medium
Some important points
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FC
Classification Based on Nature of Interaction between Dispersed Phase and Dispersion Medium
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440
FC
Classification Based on Nature of Interaction between Dispersed Phase and Dispersion Medium
Lyophilic (solvent attracting)
Lyophobic (solvent repelling)
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441
FC
Classification Based on Nature of Interaction between Dispersed Phase and Dispersion Medium
Lyophilic (solvent attracting)
Lyophobic (solvent repelling)
If water is the dispersion medium - Hydrophilic
If water is the dispersion medium - Hydrophobic
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Lyophilic Colloids (solvent attracting)
12C05.4 Colloids
443
Lyophobic Colloids (solvent repelling)
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FC
Classification Based on Type of Particles of the Dispersed Phase
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FC
Classification Based on Type of Particles of the Dispersed Phase
Multimolecular
colloids
12C05.4 Colloids
446
FC
Classification Based on Type of Particles of the Dispersed Phase
Multimolecular
colloids
Macromolecular
colloids
12C05.4 Colloids
447
FC
Classification Based on Type of Particles of the Dispersed Phase
Multimolecular
colloids
Macromolecular
colloids
Associated
colloids (Micelles)
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Multimolecular Colloids
Def. When a large number of atoms or smaller molecules aggregate together to form colloidal species, the new species is termed as Multimolecular colloid.
E.g. gold sol and Sulphur (S8) sol
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449
FC
Macromolecular Colloids
Def. When in a solution the size of the macromolecules is in the colloidal range, the system is termed as Multimolecular colloid
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450
FC
Macromolecular Colloids
Def. When in a solution the size of the macromolecules is in the colloidal range, the system is termed as Multimolecular colloid
These colloids are quite stable and resemble true solutions in many respects
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451
FC
Macromolecular Colloids
Def. When in a solution the size of the macromolecules is in the colloidal range, the system is termed as Multimolecular colloid
E.g. Natural - Starch, cellulose, proteins and enzymes, etc.
Man made - Polythene, nylon, polystyrene, synthetic rubber, etc.
These colloids are quite stable and resemble true solutions in many respects
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FC
Associated colloids (Micelles)
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FC
Associated colloids (Micelles)
Some substances like soaps at low concentrations behave as normal strong electrolytes
At higher concentrations the aggregate and show colloidal behaviour
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454
FC
Associated colloids (Micelles)
Some substances like soaps at low concentrations behave as normal strong electrolytes
At higher concentrations the aggregate and show colloidal behaviour
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455
FC
Associated colloids (Micelles)
Some substances like soaps at low concentrations behave as normal strong electrolytes
At higher concentrations the aggregate and show colloidal behaviour
Micelle
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456
FC
Conditions for Micelle formation ❓
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FC
Conditions for Micelle formation ❓
Kraft temperature (Tk)
Critical micelle concentration (CMC)
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FC
Conditions for Micelle formation ❓
Kraft temperature (Tk)
Critical micelle concentration (CMC)
The temperature above which micelles formation takes place
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Conditions for Micelle formation ❓
Kraft temperature (Tk)
Critical micelle concentration (CMC)
The temperature above which micelles formation takes place
The Concentration above which micelles formation takes place
For soap CMC is 10–4 to 10–3 mol L–1
FC
PSV
CT
CV 3
Mechanism of Micelle formation
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463
Mechanism of micelle formation
This mechanism can be explained with the example of soap solutions
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Mechanism of micelle formation
This mechanism can be explained with the example of soap solutions
Soap
Def. Soap is sodium or potassium salt of a higher fatty acids.
Generally, given as RCOO–Na+
E.g., sodium stearate CH3(CH2)16COO–Na+, which is a major component of many bar soaps
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Properties of soap
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Representation of soap
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Representation of soap
Sodium stearate (C17H35COO–Na+) - before dissociation
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Representation of soap
Sodium stearate (C17H35COO–Na+) - before dissociation
Sodium stearate (C17H35COO–Na+) - after dissociation
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Representation of soap
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Representation of soap
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Representation of soap
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FC
Micelles Formation
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FC
Micelles Formation
Polar RCOO– ions are present on the surface with their COO– groups in water and the hydrocarbon chains R staying away from it and remain at the surface
Below CMC
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FC
Micelles Formation
Polar RCOO– ions are present on the surface with their COO– groups in water and the hydrocarbon chains R staying away from it and remain at the surface
Below CMC
Arrangement of RCOO– below CMC
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475
FC
Micelles Formation
anions are aggregate to form a spherical shape with their hydrocarbon chains pointing towards the centre of the sphere with COO– part remaining outward on the surface of the sphere
Abow CMC
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476
FC
Micelles Formation
anions are aggregate to form a spherical shape with their hydrocarbon chains pointing towards the centre of the sphere with COO– part remaining outward on the surface of the sphere
Abow CMC
Arrangement of RCOO– above CMC
CV 4
Cleansing action of Soap
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478
Cleansing Action of Soaps
12C05.4 Colloids
479
Cleansing Action of Soaps
Soap
Hydrophobic
Hydrophilic
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Cleansing Action of Soaps
Soap
Hydrophobic
Hydrophilic
Cleansing action of soap is due to micelle formation around grease or oil droplet in such a way that hydrophobic part of the stearate ions is in the oil hydrophilic part projects out of the oil
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Cleansing Action of Soaps
Dirt - grease or oil
Soap
Hydrophobic
Hydrophilic
Cleansing action of soap is due to micelle formation around grease or oil droplet in such a way that hydrophobic part of the stearate ions is in the oil hydrophilic part projects out of the oil
12C05.4 Colloids
482
Cleansing Action of Soaps
PSV
CT
CV 4
Preparation of Colloids
12C05.4 Colloids
486
FC
Preparation of Colloids
12C05.4 Colloids
487
FC
Preparation of Colloids
1 - Chemical methods
2 - Electrical disintegration or
Bredig’s Arc method
3 - Peptization
12C05.4 Colloids
488
FC
Chemical Methods
12C05.4 Colloids
489
FC
Chemical Methods
Double Decomposition
Oxidations
Reduction
Hydrolysis
12C05.4 Colloids
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FC
Chemical Methods
Double Decomposition
Oxidations
Reduction
Hydrolysis
Chemical change in which two compounds in a solution react to form two new compounds by the mutual exchange of radicals
12C05.4 Colloids
491
FC
Chemical Methods
Double Decomposition
Oxidations
Reduction
Hydrolysis
Oxidation is gaining oxygen or loss of electrons
Equation
12C05.4 Colloids
492
FC
Chemical Methods
Double Decomposition
Oxidations
Reduction
Hydrolysis
Reduction is gaining hydrogen or gain of electrons
Equation
12C05.4 Colloids
493
FC
Chemical Methods
Double Decomposition
Oxidations
Reduction
Hydrolysis
Chemical breakdown of a compound due to reaction with water
Equation
12C05.4 Colloids
494
FC
Electrical disintegration or Bredig’s Arc method
12C05.4 Colloids
495
FC
Electrical disintegration or Bredig’s Arc method
Electric arc is struck between electrodes of the metal immersed in the dispersion medium
12C05.4 Colloids
496
FC
Electrical disintegration or Bredig’s Arc method
Electric arc is struck between electrodes of the metal immersed in the dispersion medium
Bredig’s Arc method
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497
FC
Electrical disintegration or Bredig’s Arc method
Electric arc is struck between electrodes of the metal immersed in the dispersion medium
The intense heat produced evaporates the metal
Bredig’s Arc method
12C05.4 Colloids
498
FC
Electrical disintegration or Bredig’s Arc method
Electric arc is struck between electrodes of the metal immersed in the dispersion medium
The intense heat produced evaporates the metal
Vapour of metal can be converted to colloidal size by condensation
Bredig’s Arc method
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Peptization
12C05.4 Colloids
500
Peptization
Def. Peptization is the process of converting a precipitate (ppt.) into colloidal sol by shaking it with dispersion medium in the presence of an electrolyte
12C05.4 Colloids
501
Peptization
Def. Peptization is the process of converting a precipitate (ppt.) into colloidal sol by shaking it with dispersion medium in the presence of an electrolyte
The electrolyte used for this purpose is called peptizing agent
This method is generally applied to convert freshly prepared ppt. into colloidal sol
12C05.4 Colloids
502
FC
Mechanism of Peptization
12C05.4 Colloids
503
FC
Mechanism of Peptization
Precipitate
Dispersion medium
Electrolyte
+
+
12C05.4 Colloids
504
FC
Mechanism of Peptization
Precipitate adsorbs one of the ions of the electrolyte on its surface
Precipitate
Dispersion medium
Electrolyte
+
+
12C05.4 Colloids
505
FC
Mechanism of Peptization
Precipitate adsorbs one of the ions of the electrolyte on its surface
This causes the development of positive or negative charge on precipitates
Precipitate
Dispersion medium
Electrolyte
+
+
12C05.4 Colloids
506
FC
Mechanism of Peptization
Precipitate adsorbs one of the ions of the electrolyte on its surface
This causes the development of positive or negative charge on precipitates
Precipitate breaks up into smaller particles of the size of a colloid
Precipitate
Dispersion medium
Electrolyte
+
+
PSV
CT
12C05.1 Adsorption and its type
: Reference Questions :
Exercise Questions : 5.9, 5.11, 5.12, 5.14, 5.18, 5.25 ( NCERT page no. 148)
Workbook Questions : 6, 10
509
12C05.
Purification, Properties and Applications of Colloids
12C05.5 Purification, Properties and Applications of Colloids
511
CV 1
Purification of Colloidal Solutions
12C05.5 Purification, Properties and Applications of Colloids
513
Purification of Colloidal Solutions
The process used for reducing the amount of impurities to a requisite minimum is known as purification of colloidal solution
Why is purification necessary❓
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514
Methods of Purifications
Dialysis
Electro dialysis
Ultrafiltration
By membrane
By electricity
By ultra filter paper
12C05.4 Colloidal state
515
types
True solution
Suspension
Cant separate particles
Easily separa particles
Colloids
12C05.4 Colloidal state
516
types
True solution
Suspension
Cant separate particles
Easily separa particles
Colloids
12C05.4 Colloidal state
517
types
True solution
Suspension
Cant separate particles
Easily separa particles
Colloids
12C05.4 Colloidal state
518
types
True solution
Suspension
Cant separate particles
Easily separa particles
Colloids
12C05.4 Colloidal state
519
types
True solution
Suspension
Cant separate particles
Easily separa particles
Colloids