Question

In heterogeneous catalysis:

• A. None of the above
• B. The catalyst and the reactants should be gases.
• C. Catalysts and reactants are in same phases.
• D. Catalysts and reactants are in different phases.

Answer 1

The correct option is D Catalysts and reactants are in different phases.

Catalyst can be classified into many types based on different parameters.
On the basis of phases, the catalyst is of two types,
1. Homogeneous catalyst
2. Heterogeneous catalyst


Heterogeneous catalyst:
When catalysts and reactants are in different phase​, then the catalyst is called heterogeneous catalyst and the process is called heterogeneous catalysis.

Example:
$2S{O}_2\left(g\right)+O_2\left(g\right)\stackrel{Pt\left(s\right)}{⟶}2S{O}_3\left(g\right)$​
Here, $Pt$ act as catalyst and it is in different phase than reactants. Hence, it is a heterogeneous catalyst.