CBSE Class 12-science Answered

The order of a reaction cannot be deduced from the chemical equation of the reaction. Reactions in heterogenous system usually follow zero order kinetics. In such a system the reactants are adsorbed on the surface of a solid catalyst. At low concentrations of the reactant, the rate of the reaction depends on the fraction of the surface covered by the reactant. However, at higher concentrations the surface of the catalyst becomes fully covered and any further increase in the concentration of the reactants does not affect the rate of the reaction.