Question

Give a balanced equation for : A thermal decomposition reaction involving heat on limestone [calcium carbonate].

Answer 1

Hint: In thermal decomposition reaction, when a substance is heated, it breaks into two or more elements/compounds. When the reactant is heated, the added heat provides the activation energy for the decomposition reaction.

Complete Step by step answer: Thermal decomposition reaction is an endothermic reaction as heat energy is added to the reaction mixture. The added heat energy is used to break the chemical bonds. When the chemical bonds in a molecule are broken, the molecule itself is broken into constituent elements.
In an endothermic reaction, heat energy is added, whereas in an exothermic reaction, heat energy is given out.
Calcium carbonate undergoes thermal decomposition to form calcium oxide and carbon dioxide. The temperature to which calcium carbonate is heated is around $1373\text{ K}$.

$\text{CaC}{\text{O}}_3\left(s\right)\stackrel{\mathrm{\Delta }}{\to }\text{ CaO}\left(s\right)\text{ + C}{\text{O}}_2\left(g\right)$

Thermal decomposition of calcium carbonate is used for manufacturing quicklime. Quicklime has several industrial applications. Quick lime is calcium oxide. It is also called burnt lime. Decomposition of calcium carbonate to calcium oxide and carbon dioxide is carried out in a rotary kiln or a shaft furnace. Carbon dioxide gas escapes and calcium oxide is left behind.

Note: A decomposition reaction is the chemical reaction in which one reactant breaks into two or more products. Decomposition reactions are mainly of three types, thermal decomposition, electrolytic decomposition and photochemical decomposition. For the decomposition process, thermal decomposition, electrolytic decomposition and photochemical decomposition uses heat energy, electrical energy and light energy respectively.