1. What is adsorption? Give one example.
Answers : Adsorption : Adsorption is surface phenomenon. Accumulation or concentration of a substance on the surface of a solid or a liquid is known as adsorption.
i) When charcoal is added to an aqueous solution of acetic acid, acetic acid will be adsorbed on the charcoal.
ii) Pt or Ni metals adsorb the gases during hydrogenation of oils.
2. What is absorption. Explain with one examples.
Answers : Absorption : Absorption is bulk phenomenon. The uniform distribution of a gas or a liquid or a solute present in a solution into the bulk of a solid or liquid is known as absorption.
Ex: A chalk piece dipped in a coloured ink absorbs the coloured substance. A sponge placed in water absorbs water into it.
3. What is meant by sorption?
Answers : The process in which both absorption and adsorption take place simultaneously is called sorption. Concentration of a substance on the surface and in the bulk of another substance is known as sorption.
Ex: Hydrogen is absorbed as well as adsorbed by palladium.
4. What is meant by Occlusion? Give an example.
Answers : The process of sorption of a gas by a metal is called occlusion.
Ex: Hydrogen gas is adsorbed as well as absorbed by palladium.
5. What is auto catalysis?
Answers : The process by which one of the intermediate products formed in the reaction itself functions as a catalyst for the reaction which is known as autocatalysis.
Ex: a) Decomposition of Arsene. Initially Arsenic formed which acts as auto catalyst
2 As H3 g 2 As + 3H2
6. What is Browmian movement?
Answers : The ceaseless chaotic and random motion of colloidal particles in a colloidal solution is called as Brownian movement
All colloidal particles exhibit this motion. The motion becomes less vigorous as the size of the particle increases and also with the viscosity of the dispersion medium. It increases with temperature.
7. What is emulsifying agent?
Answers : The third substance added to an emulsion to stabilise the emulsion is called emulsifier or emulsifying agent. Emulsifier reduces the interfacial tension between the two liquids.
Eg: 1) Soap is emulsifier for kerosene in water emulsion
2) Solid mercuric iodide (HgI2) is the emulsifier for water in benzene emulsion.
8. What is coagulation?
Answers : The phenomenon of precipitation of a colloidal solution by the addition of Electrolyte is called coagulation or flocculation.
9. What is Colloidion solution?
Answers : It is a 4% solution of nitro cellulose in a mixture of alcohol and ether.
10. What is CMC and Kraft temperature?
Answers : The formation of micelles takes place only above a particular concentration of particles
called critical micelle concentration. Kraft temperature is the minimum temperature above which the formation of micelletakes place
1. Write the differences between physical and chemical Adsorption ?
1. The forces responsible are weak Vander Waal’s forces
2. Decreases with increase in temperature
3. Heat of adsorption is low (20 – 40 kj/mole)
4. It is reversible process
5. This adsorption occurs as multilayered
6. It is not specific
7. Activation energy of adsorption is low
1. The forces responsible are strong chemical forces.
2. Increases with increase in temperature
3. Heat of adsorption is high (40- 400 kj./mole)
4. It is irreversible process
5. It is unilayered
6. It is highly Specific
7. Activation energy of adsorption is high
2. What is catalysis? How is catalysis classified? Give two examples for each.
Answers :
Catalysis : A substance which alters the rate of a chemical reaction without itself being consumed in the process, is called a catalyst. The action of catalyst in altering the rate of a chemical reaction is called catalysis.
Type of catalysis : Catalysis is classified into two types as
a) Homogeneous catalysis and
b) Heterogeneous catalysis
Homogeneous catalysis : The catalytic process in which the catalyst is present in the same phase as that of reactants, is known as homogeneous catalysis.
Heterogeneous catalysis : The catalytic process in which the catalyst and reactants are in different phase is known as heterogeneous catalysis.
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