Question

Silver chloride undergoes decomposition in the presence of light:
(A) True
(B) False

Answer 1

Hint: Any silver halide, silver chloride or silver bromide break down to form silver metal and the halogen gas. This reaction is also known as photodecomposition or photo dissociation or photolysis reaction.


Complete step by step solution:
Decomposition reaction is the process of dissociation of one chemical entity into two or more fragments. Decomposition reaction is of three types:
Thermal decomposition- the process in which one chemical substance dissociate into two or more chemical substances in the presence of heat.
Electrolytic decomposition- the process in which one chemical substance dissociates into two or more chemical substances by passing electric current.
Photo decomposition- the process in which one chemical substance dissociate into two or more chemical substances in the presence of sunlight.
Any silver halide, silver chloride or silver bromide undergoes disproportionation reaction In the presence of sunlight to form silver metal and a halogen gas.
The reaction involved is as follow:
\[\begin{align}
  & AgCl(sunlight)\to Ag+C{{l}_{2}} \\
 & AgBr(sunlight)\to Ag+B{{r}_{2}} \\
\end{align}\]
The balanced chemical reaction are:
\[\begin{align}
  & 2AgCl(sunlight)\to 2Ag+C{{l}_{2}} \\
 & 2AgBr(sunlight)\to 2Ag+B{{r}_{2}} \\
\end{align}\]
Silver chloride and silver bromide both are water insoluble and they are known for their sensitivity to light, they dissociate immediately into silver and halogen. This property of silver bromide and silver chloride allowed it to become the basis of the modern photographic material. It is used in black and white photography. This reaction is also known as photodecomposition or photo dissociation or photolysis reaction.


Hence the correct option is (B) true.



Note: The reactions involved in photographic plate for AgCl is mentioned below:
Electron ejected from chlorine the process of oxidation takes place,
\[A{{g}^{+}}+C{{l}^{-}}+\text{light energy}\to \text{A}{{\text{g}}^{+}}+Cl+1electron\]
Electrons are captured by silver; the process of reduction takes place, which leads to formation of dark images on film.
\[A{{g}^{+}}+1electron\to \text{Ag(metal)}\]