Substance which increases the rate of a chemical change but does not undergo any change itself is called a __________________

Definition

A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change is known as a catalyst.

Example

• The Haber process is the major procedure for the synthesis of ammonia(${\mathrm{NH}}_3$).
• During the reaction, Nitrogen (${\mathrm{N}}_2$) and Hydrogen(${\mathrm{H}}_2$) combine to form Ammonia (${\mathrm{NH}}_3$) in the presence of catalyst sponge Iron($\mathrm{Fe}$).

Chemical equation:

${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\stackrel{\mathrm{Fe}}{\rightleftharpoons }2{\mathrm{NH}}_3\left(\mathrm{g}\right)+\mathrm{Heat}$