Question

5 (a). By giving an example define exothermic reaction.

Answer 1

Part 1: Exothermic reaction

• Exothermic reactions are those chemical reactions that proceed with the release of heat energy from the system to the surroundings.

Part 2: Example of exothermic reaction

• The neutralization of Hydrochloric acid reacts with Sodium hydroxide solution to form Sodium chloride (salt) and water with the evolution of a lot of heat.
• $\underset{\mathrm{Hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{\mathrm{NaOH}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Sodium}\mathrm{chloride}}{\mathrm{NaCl}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}+\mathrm{Heat}$
• A neutralization reaction is an example of an exothermic reaction.