Question

Give any four differences between Physisorption and Chemisorption

Answer 1

We need to realize that the phenomenon of pulling in and holding the particles of a substance present on the fluid surface (or) solid surface prompting higher concentration of the atoms present on a superficial level is called adsorption. A portion of the reasons for adsorption are unbalanced attractive force or free valencies that are available at the outside of fluid (or) surface of strong, have the property to draw in and hold the gas atoms or a broken up substance on to their surfaces with which they come in contact.

Complete step by step answer:
We need to know that that adsorption is a surface phenomenon. During the time spent adsorption, the substance is just recollected on the surface level and doesn't go into the mass (or) solid inside (or) fluid inside. The concentration of the adsorbed particle is consistently higher at the free stage. Adsorption is quick at the outset and it gets delayed down close to the balance.
We need to comprehend that adsorption happens with the liberation of heat. In view of Le-Chatelier's rule there would be abatement in size of adsorption with increment in temperature.
There are two types of adsorption. They are physical adsorption and chemical adsorption.

Physisorption	Chemisorption
Physisorption takes place at lower temperature and decreases with increase in temperature	Chemisorption takes place at all temperatures, the adsorption increases with increase in temperature
Force of attraction in physisorption is Vander Waal’s force	Force of attraction in chemisorption is chemical bond forces
Physisorption is reversible	Chemisorption is irreversible
Heat of adsorption is small	Heat of adsorption is more
Adsorption is multilayer	Adsorption is single layer
Activation energy is not needed	Activation energy is needed

Note:
Generally physisorption is favored by low temperature and chemisorption is favored by high temperatures. The heat of adsorption in physisorption is nearly $20kJ/mol - 40kJ/mol$ whereas in chemisorption heat of adsorption is $80kJ/mol - 240kJ/mol$. The process of physisorption happens due to the formation of van der Waals force and chemisorption occurs because of the chemical bond formation.