Question

Give one word for the following :

Chemical reactions in which heat is absorbed

Answer 1

Endothermic reaction:

• A chemical reaction that proceeds with the absorption of the heat energy is called an endothermic reaction.
• Heat absorbed is used for breaking old bonds.
• In general an endothermic reaction can be represented as
• $\mathrm{A}+\mathrm{B}\stackrel{}{\to }\mathrm{C}+\mathrm{D}-\mathrm{Q}\mathrm{kcal}(\mathrm{heat}\mathrm{evolved})$
• For example thermal decomposition of calcium carbonate(${\mathrm{CaCO}}_3$)
• $\underset{\mathrm{calcium}\mathrm{carbonate}}{{\mathrm{CaCO}}_3\left(\mathrm{s}\right)}\stackrel{\mathrm{heat}}{\to }\underset{\mathrm{calcium}\mathrm{oxide}}{\mathrm{CaO}\left(\mathrm{s}\right)}+\underset{\mathrm{carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}-\mathrm{heat}\mathrm{energy}$