Adsorption and absorption. Give one example.

Adsorption :

• Adsorption is a surface phenomenon as adsorbed matter is concentrated only at the surface and does not penetrate through the surface to the bulk of adsorbent.
• Concentration of the adsorbate is high only at the surface of the adsorbent.
• It is dependent on temperature and pressure.
• It is accompanied by evolution of heat known as heat of adsorption.
• It depends on surface area. e.g. Adsorption of a gas or liquid like acetic acid by activated charcoal.

 Absorption :

• Absorption is a bulk phenomenon as absorbed matter is uniformly distributed inside as well as at the surface of the bulk of substance.
• Concentration of the absorbate is uniform throughout the bulk of the absorbent.
• It is independent of temperature and pressure.
• It may or may not be accompanied by any evolution or absorption of heat.
• It is independent of surface area. e.g. Absorption of water by cotton, absorption of ink by blotting paper.