Question

Which kind of catalysis can be explained on the basis of adsorption theory?
A.Homogenous catalysis
B.Heterogeneous catalysis
C.Negative catalysis
D.Auto catalysis

Answer 1

The accumulation of molecules on the surface rather than on the bulk of the solid or the liquid is termed as adsorption. The catalytic process in which the reactants and the catalyst are in different phases is known as heterogeneous catalysis. Here rather than being absorbed or mixing the catalyst remains on the surface and does the action.

Complete step by step answer:
In adsorption, the adsorbate which is adsorbed remains only on the surface rather than being mixed in the bulk of the adsorbent.
Heterogeneous catalysis involves the reactant and the catalyst to be in different phases.
The theory of heterogeneous catalysis states that the reactants in the gaseous or solution phases are adsorbed on the surface of the solid catalyst.
The increase in the concentration of reactants on the surface of the catalyst increases the rate of the reaction.
Due to the exothermic nature of the reaction the heat released is used in the enhancement of the rate of the reaction.
The catalytic action can be understood in terms of intermediate compound formation.
First, the reactants are adsorbed on the surface of the catalyst. Here the chemical reaction occurs on the surface through the formation of the intermediate.
The reaction products are then desorbed from the catalyst surface freeing the space for further reaction. The reaction products finally diffuse away from the surface of the catalyst.
This theory explains how the catalyst remains unchanged in mass and chemical composition at the end of the reaction and its effectiveness even in small quantities.
The surface of the catalyst has free valencies which provide the place for the chemical forces of attraction. When the gas comes in contact with such a surface its molecules are held through weak chemical forces and thus may react if the molecules happen to be different.
Thus the newly formed products can evaporate leaving the surface of the catalyst.

So, the correct answer is Option B.

Note: The process of adsorption is a surface phenomenon.
The reactants are adsorbed on the surface of the catalyst.
The heat released during the reaction is used to increase the rate of the reaction.
The reaction moves forward by the formation of intermediate compounds.