Question

Which among the following changes are exothermic or endothermic in nature?

(c) Dissolution of sodium hydroxide in water

Answer 1

Exothermic reaction

• Exothermic reactions are reactions in which heat energy is released in the form of light or heat.

Endothermic reaction

• Endothermic reactions are reactions in which heat energy is absorbed.

Dissolution of sodium hydroxide in water

• Dissolution of sodium hydroxide in water in water is as follows:-
• $\mathrm{NaOH}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{Na}}^{+}\left(\mathrm{aq}\right)+{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)$
• Sodium hydroxide$\left(\mathrm{NaOH}\right)$ is one of the strongest bases.
• So, when we add the NaOH into the water, a huge amount of heat evolves.
• Hence, the dissolution of sodium hydroxide is an exothermic reaction.