Freundlich Adsorption Isotherm

Freundlich gave an empirical mathematical relationship between the extent of adsorption x/m and the equilibrium pressure (p) of the gas.

In this relation k is a constant at a given temperature and depends upon the nature of the adsorbate and adsorbent. The value of nchanges with pressure. It is 1 at low pressures and increases with pressure. The relationship is valid at a constant temperature.