Question

Which of the following reactions are exothermic in nature?

(i) Evaporation of water
(ii) Dissolution of sodium hydroxide in water
(iii) Dilution of sulphuric acid
(iv) Dissolution of ammonium chloride in water
(v) Combustion of methane gas

Answer 1

Dissolving of sodium hydroxide in water, dilution of sulphuric acid and combustion of methane gas are exothermic reactions in which a large amount of heat is released.

Reactions in which heat is released along with the formation of products are called exothermic reaction.

Evaporation of water and dissolving of ammonium chloride in water are endothermic reactions in which heat is absorbed.