Question

Is the reaction ${\mathrm{CaCO}}_3\left(\mathrm{s}\right)\to \mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$ an exothermic reaction?

Answer 1

Endothermic reaction:

• A reaction that the system absorbs energy from its surrounding in the form of heat.

Exothermic reaction:

• A reaction that releases energy from the system in the form of heat.

Decomposition reaction:

• A decomposition reaction is a chemical reaction in which one reactant breaks into two or more products.
• The general decomposition reaction is $\mathrm{AB}\to \mathrm{A}+\mathrm{B}$

Thermal decomposition of Calcium carbonate:

• Calcium carbonate undergoes thermal decomposition$\left(1373\mathrm{K}\right)$ to form Calcium oxide and Carbon dioxide.
  $\underset{\mathrm{Calcium}\mathrm{carbonate}}{{\mathrm{CaCO}}_3\left(\mathrm{s}\right)}\stackrel{1373\mathrm{K}}{\to }\underset{\mathrm{Calcium}\mathrm{oxide}}{\mathrm{CaO}\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}$
• When the decomposition of calcium carbonate occurs heat is absorbed, so this is an endothermic reaction.
• A decomposition reaction is a chemical reaction in which a single compound breaks down into two or more elements or new compounds.

Therefore, the thermal decomposition of Calcium carbonate is endothermic.