Question

Write one equation each for decomposition reactions where energy is supplied in the form of heat, light, or electricity.

Answer 1

Decomposition reaction:

• When the reactants break down in the presence of heat, light, and electricity into two or more products, this reaction is termed a decomposition reaction.
• The general decomposition reaction can be depicted as:

$\mathrm{AB}\stackrel{\mathrm{Heat}/\mathrm{Electricity}/\mathrm{Light}}{\to }\mathrm{A}+\mathrm{B}$

Decomposition reaction can be categorized into three types which are as follows:

1. Thermal decomposition reaction:

• The decomposition reaction that takes place in the presence of thermal energy or heat is known as a thermal decomposition reaction.
• An example of a thermal decomposition reaction is as follows:

${\mathrm{CaCO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$

2. Photo decomposition:

• The decomposition reaction that takes place in the presence of light is known as a photodecomposition reaction.
• An example of a photodecomposition reaction is as follows:

$2{\mathrm{H}}_2{\mathrm{O}}_2\left(\mathrm{l}\right)\stackrel{\mathrm{light}}{\to }2{\mathrm{H}}_2\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)$

3. Electrolytic decomposition:

• The decomposition reaction that requires activation energy for decomposition which is provided by the thermal energy, is known as electrolytic decomposition.
• An example of electrolytic decomposition is as follows:
• $2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$