Question

Give two example in case of chemical action due to light.

Answer 1

Photolytic decomposition reactions takes place in the presence of light.

The decomposition of silver chloride into silver and chlorine is caused by light energy.

$\underset{\mathrm{silver}\mathrm{chloride}}{\underset{}{2\mathrm{AgCl}}}\to \underset{\mathrm{silver}}{\underset{}{2\mathrm{Ag}}}+\underset{\mathrm{chlorine}}{\underset{}{{\mathrm{Cl}}_2}}$

Another example is the synthesis of chloro methane from methane and chlorine, which is initiated by light.

$\underset{\mathrm{mathane}}{\underset{}{{\mathrm{CH}}_4\left(\mathrm{g}\right)}}+\underset{\mathrm{chlorine}}{\underset{}{{\mathrm{Cl}}_2\left(\mathrm{g}\right)}}+\mathrm{Light}\mathrm{energy}\to \underset{\mathrm{Chloromethane}}{\underset{}{{\mathrm{CH}}_3\mathrm{Cl}\left(\mathrm{g}\right)}}+\underset{\mathrm{hydrogen}\mathrm{chloride}}{\underset{}{\mathrm{HCl}\left(\mathrm{g}\right)}}$