Class 12th

5.20 

Associated colloids- They formed by aggregation of large number of ions. instead of atoms or molecules in above two colloids. They have van there waals force directly proportional to concentration of ions. Ex- Soap Sol.

5.18 

Temperature- Adsorption decreases with increase of temperature because it is an exothermic process, by using le chatelier's principle the reaction will proceed in backward direction.

Pressure- Adsorption increase with increase in pressure at constant temperature.

5.17

Colloidal solutions get classified in 8 Types on the basis of physical state of the dispersed phase and dispersion medium. This are given in following table-

5.16

When adsorbate (gas or liquid mostly) absorbed then their entropy get reduced i.e. ΔS is negative. For every spontaneous process ΔG must be negative. ΔG = ΔH - TΔS, as TΔS is positive (ΔS is negative) ΔH must be negative in order to make ΔG negative. Hence ΔH is negative that means the reaction is exothermic. Hence every adsorption reactions are exothermic.

5.15 

Adsorption of reactants on the solid surface of the catalysts increases the rate of reaction. Generally, the reactant is gas whereas catalyst is solid. Reactant molecules get adsorbed on the surface of the catalyst as a result concentration of reactant increases leads to increase in the rate of reaction.

There are many important reactions is based on this, for Ex (1) manufacturing of ammonia using iron as a catalyst,

2. manufacture of H₂SO₄ By contact process,

3. use of finely divided Nickel in the hydrogenation of cells

5.14 

Increasing the adsorbing power of adsorbent is known as activation of adsorbent.it can be achieved by

Increase in surface area of

By dividing the adsorbent into small

By making its surface

5.12 

Extent of adsorption of a gas on a solid is influenced by following factors-

Nature of adsorbate

Nature of adsorbent

Pressure

Temperature

5.11

Finely divided substances have large surface area compared to not divided substance. And the increase in surface area increases the adsorption. Hence Finely divided substances are more effective adsorbent.