CBSE Class 12 Chemistry Notes: Surface Chemistry – Difference between adsorption and absorption

Difference between adsorption and absorption:-

Sorption:-If the adsorption and absorption takes place simultaneously then the process is named as sorption.

Negative adsorption:-When the concentration of the adsorbate is more on the surface of adsorbent then in the bulk, it is called adsorption if the concentration of adsorbate increases in the bulk after adsorption it is called negative adsorption.

Factors affecting the adsorption of gases by solids:-

1. Nature and surface area of adsorbent: -at the same temperature greater is the surface area of adsorbent greater is theadsorption. Example charcol, silica are good adsorbent due their pourous structure and area.
2. Nature of gas:- it is given that higher the critical temperature of the gas greater is its adsorption or more easily a gas is liquefiable or more soluble in water more is its adsorption.
3. Tempreture:-adsorpation of any particular gas by some particular adsorbent is decreases with the increase in the tempreture.
   Example:- one gram of charcol adsorbes about |m| of N2 at 273 K, 20ml at 244 K, us ml at 195K.
   Thus the amount of heat evolved when one mole of the gas is adsorbed on the adsorbent is called as the heat of adsorption.
4. Pressure:- At constant temperature the adsorption of a gas is increases with the increase with the increase in the pressure.

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