What is adsorption ? Discuss the mechanism of adsorption of gases on solids.

Explanation

Adsorption : The accumulation (or) concentration of a substance on the surface rather than in the bulk of solid (or) liquid is known as adsorption.
Eg : Adsorption of gases like `O_(2), H_(2), C_(12)` etc., on charcoal.
Mechanism of Adsorption :
`to` Adsorption arises due to the fact that the surface particles of the adsorbent are not in the same environment as the particles inside the bulk.
`to` Adsorbent possess unbalanced or residual attractive forces. These forces responsible for attracting the adsorbate molecules on adsorbent surface.
`to` The extent of adsorption increases with increase in surface area of adsorbent at a given temperature and pressure.
`to` During the adsorption, there is always a decrease in residual forces of the surface. There is decrease in surface energy which appears as heat. So, Adsorption is always Exothermic.
`to` Adsorption is accompanied by decrease in enthalpy as well as decrease in entropy of system.
`to` As the adsorption proceeds `DeltaH` becomes less and less negative, ultimately, `DeltaH` becomes equal to `TDeltaS` and `DeltaG` becomes zero. At this state equilibrium is attained.