Question

Differentiate between physical and chemical adsorption?

Answer 1

Adsorption: Adsorption is a process that involves the accumulation of a substance in molecular species in higher concentrations on the surface.

Adsorbate: Substance that is deposited on the surface of another substance. For example, ${\mathrm{H}}_2$, ${\mathrm{N}}_2$ and ${\mathrm{O}}_2$ gases.

Adsorbent: Surface of a substance on which adsorbate adsorbs. For Example, Charcoal, Silica gel, and Alumina.

Physical adsorption	Chemical adsorption
1. It is due to weak Van der Waals forces between adsorbate and adsorbent.	1. It is due to strong chemical forces of bonding type between adsorbate and adsorbent.
2. It is reversible in nature.	2. It is irreversible in nature.
3. Adsorption will decrease by increasing temperature.	3. Adsorption increases by an increase in temperature.
4. Increase in pressure will increase adsorption.	4. Pressure has no effect.
5. This adsorption is a multi-layered process.	5. This type of adsorption is almost a single-layered phenomenon.
6. Examples: H2 and N gases adsorb on coconut charcoal.	6. Examples: Charcoal, Silica gel, Alumina.