Difference between Adsorption and Absorption

Adsorption	Absorption
It is surface phenomena.	It is bulk phenomena.
Molecules are present more over the surface then bulk	Molecules are evenly distributed.
Initially rate of adsorption is fast then it decreases.	The rate if adsorption is same through out the surface.
Ex.-adsorption of water vapourBy silica gel.	Ex-Adsorption of water by CaCl2(Anhydrus CaCl₂).

Types of adsorption :- It is two types :-

(i). Physical adsorption (Physisorption) :- It has following characteristic :-

It is non-specific in nature.
Adsorbed and adsorbent are held together by weak Vander waal’s force.
As the temperature increases rate of adsorption decreases due to increase in kinetic energy of gaseous molecule.
As the pressure increases rate of adsorption increases because in such case multi-molecular layer in obtained.
It forms Multimolecular layer.

It is specific in nature it means specific adsorbed adsorb over specific adsorbent.
Adsorbed are held over the adsorbent through chemical bond.
Temperature :- In such adsorption initially rate of adsorption increases by increase in temperature because for chemical reaction molecules are required energy that is known as activation energy so after getting activation energy,further increase in temperature rate of adsorption desorption decreases.
Pressure :- Initially increase in pressure increases the rate of adsorption further increases in pressure rate of adsorption does not change. It Happens because when adsorbed covered the adsorbent so no surface is exposed for further adsorption that’s why further increase in pressure has no effect.
It forms Unimolecular layer.