Question

What happens when silver chloride is exposed to sunlight? Write a chemical equation for this reaction. Also give one use of such a reaction.

Answer 1

When white silver chloride is exposed to sunlight, it undergoes a photochemical decomposition reaction. The light energy causes the compound to break down, turning the white solid into a grayish-white silver metal and releasing yellow-green chlorine gas.

\[\ce{\underset{Silver chloride}{2AgCl_{(s)}} ->[Sunlight] \underset{Silver}{2Ag_{(s)}} + \underset{Chlorine}{Cl2_{(g)}}}\]

This light-sensitive reaction is the foundation of black-and-white photography. Silver halides are coated onto photographic film or paper; when exposed to light, they darken to varying degrees depending on the scene’s brightness, creating a photographic image.