Physical adsorption
It takes places at low temperature and decreases with increase in temperature
Van Der Waals force is the force helding the adsorbate
it is reversible
Not specific
it forms a multimolecular layer
It is dependent of pressure and temperature
examples Clay, silica gel
Chemical Adsorption
It is specific in nature
it involves chemical bonds between the gas molecules and the adsorbent surface
it requires a certain level of energy of activation
The rate of chemical adsorption is directly proportional to the surface area
it forms a unimolecular layer
It is reversible in nature
It is slow at low temperature and occurs at a higher rate with an increase in pressure
example: Rubbing pain balm on the forehead
