Question

What is meant by decomposition reaction? Write the chemical reaction of decomposition of sugar on heating.

Hint:

Decomposition reactions are used in many industrial processes, such as the production of quicklime (CaO) from limestone (CaCO$_3$) and the breakdown of organic matter in composting.

Answer 1

A decomposition reaction is a type of chemical reaction in which a single, complex compound breaks down into two or more simpler substances. This breakdown is often initiated by energy input in the form of heat (thermal decomposition), light (photodecomposition), or electricity (electrolysis). The general form of a decomposition reaction is: \[ \text{AB} \rightarrow \text{A} + \text{B} \] Example: Decomposition of Sugar on Heating: When sugar (sucrose, C$_{12}$H$_{22}$O$_{11}$) is heated strongly, it undergoes thermal decomposition. The complex sugar molecule breaks down into its simpler components: solid carbon (C), which is the black substance left behind, and water (H$_2$O), which is released as steam. The balanced chemical reaction is: \[ \text{C}_{12}\text{H}_{22}\text{O}_{11}(\text{s}) \xrightarrow{\Delta} 12\text{C}(\text{s}) + 11\text{H}_2\text{O}(\text{g}) \] Here, $\Delta$ represents the heat applied to initiate the reaction.