Name the two groups into which phenomenon of catalysis can be divided. Given an example of each group with the chemical equation involved.

The phenomenon of catalysis is basically the ability to increase the rate of a chemical reaction, or more specifically the rate at which equilibrium is attained. This is achieved by employing a catalyst. Catalysis can be divided into two classes;

(i) Homogeneous catalysis: 

When the reactant and catalyst are in the same phase

(ii) Heterogeneous catalysis:

When the reactant and catalyst are in a different phase