Activity 1.8 Ncert Science class 10
Procedure: The concerned activity asks us to put silver chloride in sunlight for a few minutes.
Observation: Colour of silver chloride turns grey from white.
Explanation: Silver chloride in presence of light decomposes to solid silver and chlorine gas. Elemental silver is grey in colour, so a grey colour appears.
2AgCl(s) ———> 2Ag(s) + Cl2(g)
Application: Photographic film
Silver chloride (and all halides of silver) are photosensitive. They change the colour on exposure to light. This property is used in the photographic industry to make films. Films have a thin layer of silver chloride coated on them. When we click the camera, light passes through the lens to the film and image is imprinted on the film. Processing this film results in coloured photos which we keep in albums and posters.
Note: We prepare Silver chloride by mixing silver nitrate solution with sodium chloride solution. A milky white precipitate is the silver chloride.
AgNO3 + NaCl ———> AgCl↓ + NaNO3
For more knowledge on photography, you can see an article on uses of Silver chloride in photography here.