Question

Is physical adsorption specific in nature?

Answer 1

Hint: Adsorption is a surface phenomenon, which arises because of the unbalanced forces on the surface of solids and liquids. This is due to the fact that the surface particles of the adsorbent are not in the same environment as the particles inside the bulk.
Physical adsorption is reversible in nature and in physisorption no appreciable activation energy is required.

Complete answer:
When the particles of the adsorbate are held to the surface of the adsorbent by physical forces like van der Waals forces, the adsorption is known as physical adsorption or physisorption.
The attractive forces between the adsorbent and the adsorbate molecules are weak. Physical adsorption occurs readily at low temperature and decreases with an increase in temperature according to Le-Chatelier’s principle, if the temperature is increased, the kinetic energy of the gas molecules are increased, they leave the surface of the adsorbent.
Physical adsorption lacks specificity, as it is not specific and therefore, all gases are adsorbed on all solids to the same extent. Adsorbent does not show any particular preference for an adsorbate in other words it can be explained as a given surface of an adsorbent does not show any preference for a particular gas as the van der Waals forces are universal.
So, the answer to the question is physical adsorption is not specific in nature.

Note:
The phenomenon of attracting and retaining the molecules of a substance at the surface of a solid or a liquid resulting in a higher concentration of the molecules on the surface than in the bulk is known as adsorption.
The solid substance on the surface of which adsorption occurs is called adsorbent and the substance that gets adsorbed on the solid surface due to intermolecular attractions is known as adsorbate.