Question

Classify the following reaction into exothermic and endothermic reactions-

Reaction between zinc and dilute Sulphuric acid.

Answer 1

1. Exothermic reactions: The reactions in which heat (energy) is evolved are called exothermic reactions.
2. Endothermic reactions: The reactions in which heat (energy) is absorbed during a reaction are called endothermic reactions.
3. Reaction between Zinc and dilute sulphuric acid- When dilute sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$)is added to zinc ($\mathrm{Zn}$)granules, hydrogen (${\mathrm{H}}_2$)gas is evolved and zinc sulphate (${\mathrm{ZnSO}}_4$) is formed along with the release of heat.

$$\begin{gathered} \mathrm{Zn}\left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)+\mathrm{Heat} \\ \mathrm{Zinc}\mathrm{Sulphuric}\mathrm{acid}\mathrm{Zinc}\mathrm{sulphate}\mathrm{Hydrogen} \end{gathered}$$

4. Hence, the reaction between Zinc and dilute sulphuric acid is an exothermic reaction.