Role of adsorption in a catalytic reaction. The role of heterogeneous catalysis has been explained on the basis of adsorption theory postulated by Faraday.
According to it: Due to unsatisfied valences forces on the catalyst surface, the molecules of the gaseous reactants get adsorbed in unimolecular layer.Due to increased concentration of the reacting substances on the surface of the solid catalyst the chemical action is accelerated.