Question

Which one of the following is an example of homogeneous catalysis?
A. Manufacture of sulphuric acid by the contact process
B. Manufacture of ammonia by Haber's process
C. Hydrolysis of sucrose in presence of diluted hydrochloric acid
D. Hydrogenation of oil

Answer 1

Hint: If the catalyst is present in the same phase as the reactant, it is called a homogeneous catalyst and this type of catalysis is known as homogeneous catalysis.

Complete step by step answer: In the case of option A i.e. during the manufacture of sulphuric acid by contact process, the key step of the process involves the oxidation of sulphur dioxide to sulphur trioxide in the presence of platinised asbestos or $V_2{O}_5$ as the catalyst. Here reactant is present in the gaseous phase whereas the catalyst is present in the solid phase. Hence reactant and catalyst are not in the same phase hence it is an example of a heterogeneous catalyst.
In the case of option B i.e. during the manufacture of ammonia by Haber's process, one mole of nitrogen gas reacts with three moles of hydrogen gas in the presence of ion as a catalyst. Here nitrogen and hydrogen both reactants are present in the gaseous phase but the catalyst iron is present in the solid phase. Hence reactants and catalysts are in different phases hence it is also an example of a heterogeneous catalyst.
In the case of option C i.e. during the hydrolysis of sucrose in the presence of diluted hydrochloric acid, here both sucrose and diluted hydrochloric acid are in the liquid phase i.e. both reactant and catalyst are in the same phase. So it is an example of a homogeneous catalyst.
In the case of option D i.e. during the hydrogenation of oil finely divided nickel, platinum is used as the catalyst. Here vegetable oil is in the gaseous phase whereas catalyst is in the solid phase. Hence it is also an example of a heterogeneous catalyst.
So, the correct answer is “Option C”.

Note: The homogeneous catalysis is based on the intermediate compound formation theory. According to this theory, catalyst enters into a chemical combination of one or more of the reactants forming an intermediate compound which then decomposes or combines with one of the reactants to give the product.