Question

A _______ is a substance that changed the rate of chemical reaction without itself undergoing any chemical change.

Answer 1

Catalyst:

• A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change is called a catalyst.
• It reduces the activation energy of the reaction.

Some of the important characteristics of catalysts are,

• A catalyst does not initiate a chemical reaction.
• A catalyst does not be consumed in the reaction.
• Catalysts tend to react with reactants to form intermediates and at the same time facilitate the production of the final reaction product. After the whole process, a catalyst can regenerate.

For example, $\mathrm{Iron}\left(\mathrm{Fe}\right)$ act as a catalyst in a reaction known as Haber's process:

• $\underset{\mathrm{Nitrogen}}{{\mathrm{N}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Hydrogen}}{3{\mathrm{H}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{Fe}}{\rightleftharpoons }\underset{\mathrm{Ammonia}}{2{\mathrm{NH}}_3\left(\mathrm{g}\right)}+\mathrm{Heat}$
• Here, $\mathrm{Iron}\left(\mathrm{Fe}\right)$ act as a catalyst and increases the rate of the chemical reaction.

Thus, A catalyst is a substance that changed the rate of a chemical reaction without itself undergoing any chemical change.