Question

5 (b). By giving an example define endothermic reaction.

Answer 1

Part 1: Endothermic reaction:

• All chemical reaction takes place either by the absorption or the release of energy, generally in the form of heat energy.
• The chemical reactions which proceed with the absorption of heat energy are called endothermic reactions.

Part 2: Examples of endothermic reaction:

• When Sodium bicarbonate is heated strongly, it forms Sodium carbonate, water vapor, and Carbon dioxide gas. However, the reaction takes place only on heating, i.e., with the absorption of energy.
• $\underset{\mathrm{Sodium}\mathrm{bicarbonate}\mathrm{sodium}\mathrm{carbonate}\mathrm{Water}\mathrm{vapor}\mathrm{Carbon}\mathrm{dioxide}}{2{\mathrm{NaHCO}}_3\stackrel{∆}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_3+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2}$