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

Hint: On exposure to sunlight, silver chloride decomposes into silver metal and chlorine gas. It is white crystalline in appearance and naturally occurs as mineral chlorargyrite. This reaction is used in white and black photography because of the light sensitivity of silver ions.

Complete Step By Step Solution
The decomposition of silver chloride to silver and chlorine in the presence of sunlight is known as Photolytic Decomposition. The white color silver chloride decomposes to grey-white color silver metal and yellowish color chlorine gas. The chemical reaction is given as-
 $2\text{AgCl}\left(\text{s}\right)\underset{\text{Decomposition}}{\overset{\text{Light}}{\to }}2\text{AgCl}\left(\text{s}\right)+\text{C}{\text{l}}_2\left(\text{g}\right)$
Decomposition reactions are used in black and white photography. Black and white photography depends upon the light sensitive materials which are then used to produce contrasting images. The photographic film is made of silver halides which on exposure to sunlight decompose to silver and chlorine gas, the white color silver chloride turns into grey-white color silver, darkening the area of the film thus producing the black and white images.
Different tones of grey are used in black and white photography ranging from white to black color which helps in producing contrasting images. Silver bromide can also be used in such kind of photography because it also decomposes into bromine and silver on exposure to sunlight.

Note
Silver chloride is broken down by visible violet and ultraviolet light. It results in the formation of silver ion and chlorine ion. The chlorine ion has a negative charge on it so it's extra electron is ejected and then captured by silver ion which then silver metal and forms a dark image on the photographic film.