Photochemical reactions

         PHOTOCHEMICAL REACTIONS

Chemical reactions which liberate or absorb light energy are known as photochemical reactions.

Photosynthesis 

Photosynthesis is a chemical reaction that is responsible for sustaining life on earth. In this reaction, plants produce glucose by absorbing light. Note the chemical equation of this reaction.

Water + Carbon dioxide + Light —>Glucose + Oxygen

          6H2O + 6CO2 + Light —-> C6H12O6 + 6O2

The glucose thus formed is stored by plants in the form

of starch.

Colour change of silver bromide

Take some silver bromide in two dry watch glasses. Wrap one of them with a black paper. Keep both of them in sunlight for some time.

Observations:

Colour of silver bromide faded in watch glass which is placed in sunlight. This was due to the deposition of silver produced as a result of the decomposition of silver bromide by the absorption of light.