Question

What is meant by exothermic and endothermic reactions? Give examples.

Answer 1

Exothermic reactions:

• The chemical reaction in which the heat is released is known as an Exothermic reaction.
• Examples are the burning of a candle and the reaction of a strong acid with water.
• The chemical equation that is used to describe this reaction is:

$\mathrm{Reactants}\to \mathrm{Products}+\mathrm{Energy}$

Example of Exothermic reactions:

• Formation of Carbon dioxide.
• The chemical reaction can be depicted as:
• $\mathrm{C}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{CO}}_2\left(\mathrm{g}\right)+\mathrm{Heat}$

Endothermic reactions:

• The chemical reaction in which the heat is absorbed is known as an Endothermic reaction.
• Examples are melting ice cubes and melting solid salts.
• The chemical equation that is used to describe this reaction is:

$\mathrm{Reactants}+\mathrm{Energy}\to \mathrm{Products}$

Example of Endothermic reactions:

• Formation of Nitric oxide.
• The chemical reaction can be depicted as:
• ${\mathrm{N}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{\mathrm{Heat}}{\to }2\mathrm{NO}\left(\mathrm{g}\right)$