Question

'A catalyst increases the rate of a reaction but it is not consumed' because it does not participate in the reaction. Comment.

Answer 1

A catalyst is defined as a chemical substance which, on addition to a reacting system, alters the rate of the chemical reaction by by reducing activation energy, but itself remains chemically and quantitatively unchanged after the reaction.

A catalyst does not appear to take part in the chemical reaction. However, it does react and combine with one or more reactant molecules to form an intermediate complex.

Reactant + Catalyst → Complex

The complex further decomposes to form the products, thereby regenerating the catalyst.

Complex → Products + Catalyst

Thus, despite the participation of the catalyst in the chemical reaction, it does not feature in the overall balanced chemical equation. As a result, it is not consumed in the reaction.