Question

Chemical reactions in which heat is absorbed.

Answer 1

The type of reactions in which heat is either evolved or absorbed are known as Thermic reactions.

• Endothermic reactions- The reactions in which heat is absorbed during the process.

Example-

$\underset{\mathrm{Nitrogen}}{{\mathrm{N}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}+\mathrm{Heat}\to \underset{\mathrm{Nitrogen}\mathrm{oxide}}{2\mathrm{NO}\left(\mathrm{g}\right)}$

Here, Nitrogen is reacting with oxygen where heat is required for the reaction to produce nitrogen oxide.

• Exothermic reactions- The reactions in which heat is evolved during the process.

Example-

$\underset{\mathrm{Cabon}}{\mathrm{C}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\mathrm{Heat}$

Here, Carbon is burning in presence of Oxygen to give Carbon dioxide and heat is evolved during the reaction.

Hence, the answer is endothermic reaction.