Question

Catalysis can be classified into two groups-homogeneous and heterogeneous.
(A) What do you mean by homogeneous catalysis?
(B) Write one example for heterogeneous catalysis.

Answer 1

Catalysis is the process of increasing the rate of a chemical reaction with the use of a catalyst. Catalysts are not going to consume in the chemical reaction but can be used repeatedly. Only a very small amount of catalyst is sufficient to complete the reaction.

Complete step by step solution:

Catalysis can be classified into two categories

1. Homogeneous catalysis:
   - In this catalysis the physical state (phase) of the catalyst is the same as the physical state of reactants.
   - Means the catalyst and the reactants and products are in the same state either solid or liquid or gas.
   - Few examples for homogeneous catalysis are as follows.
   $2S{{O}_{2}}+{{O}_{2}}\xrightarrow{NO}2S{{O}_{3}}$
   - In the above reaction all reactants, products and catalyst all are in the same phase (gaseous state)
   $C{{H}_{3}}COOC{{H}_{3}}+{{H}_{2}}O\xrightarrow{HCl}C{{H}_{3}}COOH+C{{H}_{3}}OH$
   - In the above reaction all reactants, products, and catalyst all are in the same phase (liquid state).
2. Heterogeneous catalysis:
   - In this catalysis the physical states (phase) of the catalyst and the reactants and products are in different phases.
   - Generally, the catalyst is in solid phase (powdered form) and this type of catalysis is called surface catalysis.
   - Few examples for homogeneous catalysis are as follows.
   $2S{{O}_{2}}+{{O}_{2}}\xrightarrow{Pt}2S{{O}_{3}}$
   - In the above reaction catalyst is in solid state. The reactants and products are in a gaseous state.
   ${{N}_{2}}+3{{H}_{2}}\xrightarrow{Fe}2N{{H}_{3}}$
   - In the above reaction catalyst is in solid state. The reactants and products are in a gaseous state.

Note: Don't be confused with the words, catalysis and catalyst. Both are not the same.
Catalyst: It is a chemical substance won't be involved in the chemical reaction but increases the rate of the reaction.
Catalysis: The process of converting reactants into products in a chemical reaction with the use of a small amount of catalyst is called catalysis. The catalysis will be either homogeneous or heterogeneous catalysis.