Adsorption of gases on solid surface depends upon:

(1)    Nature of gas or adsorbent:

Adsorption $\propto$ Critical temperature of gas

or

van der Waal’s force of attraction (a)

$\underset{T_C in K}{e.g.}: \underset{430}{SO_2} > \underset{406}{NH_3} > \underset{324}{HCl} > \underset{304}{CO_2} > \underset{190}{CH_4} > \underset{133}{CO} > \underset{126}{N_2} > \underset{33}{H_2}$

(2)    Effect of Temperature: Adsorption $\propto \dfrac{1}{\text{Temperature}}$

(3)    Pressure : At constant Temperature

$\text{Adsorption} \propto \text{pressure}$

(4)    Surface area of Adsorbent: Larger the surface area of adsorbent more will be active centers and faster will be the rate of adsorption.