Question

Name the two groups into which phenomenon of catalysis can be divided. Give an example of each group with the chemical equation involved.

Answer 1

The two groups into which phenomenon of catalysis can be divided are:

(i) Homogeneous catalysis: When the reactants and the catalyst are in the same phase, the catalysis is said to be homogeneous catalysis.

For example, $S{O}_2$ is oxidised to $S{O}_3$ in the presence of nitric oxide, $NO$ as catalyst.

$2S{O}_2\left(g\right)+O_2\left(g\right)\stackrel{NO\left(g\right)}{\to }2S{O}_3\left(g\right)$

(ii) Heterogeneous catalysis: When the reactants are in a different phase than the catalyst, the catalysis is said to be heterogeneous.

For example, the combination of dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron as a catalyst.

$N_2\left(g\right)+3H_2\left(g\right)\stackrel{Fe\left(s\right)}{\to }2N{H}_3\left(g\right)$.