When calcium carbonate (\( \text{CaCO}_3 \)) is heated, it decomposes into quick lime (\( \text{CaO} \)) and carbon dioxide (\( \text{CO}_2 \)):
\[\text{CaCO}_3 \xrightarrow{\text{heat}} \text{CaO (Quick lime)} + \text{CO}_2\]
Quick lime is used in various industrial applications such as construction and steel manufacturing.