Substances, which accelerate the rate of a chemical reaction and themselves remain chemically and quantitatively unchanged after the reaction, are known as catalysts, and the phenomenon is known as catalysis.

Types of Catalysts

1. Homogeneous and Heterogeneous Catalysis

    a. Homogeneous Catalysts

A reaction in which both the Catalysts and the Reactants are in same phase, such a Catalysts is called Homogeneous Catalysts

Such as:

  •  Oxidation of sulphur dioxide into sulphur trioxide with dioxygen. Catalyst used in reaction is oxides of Nitrogen gas ( such as NO)


SO2 , O2 , SO3 and NO all are in gaseous phase all the time during the reaction process.

a. Heterogeneous Catalysts

The catalytic process in which the reactants and the catalyst are in different phases.

  • Oxidation of ammonia into nitric oxide in the presence of platinum gauze

Related Tutorials