Question

2g of silver chloride is taken in a china dish and the china dish is placed in sunlight for some time. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical reactions.

Answer 1

Decomposition reaction:

A chemical reaction in which a single substance splits into two or more simple substances under certain suitable conditions is known as a Decomposition reaction.

For example:

When Limestone$\left({\mathrm{CaCO}}_3\right)$ is heated strongly it decomposes into Calcium oxide$\left(\mathrm{CaO}\right)$ and Carbon dioxide$\left({\mathrm{CO}}_2\right)$.

${\mathrm{CaCO}}_3\left(\mathrm{s}\right)\stackrel{\mathrm{heat}}{\to }\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$.

And, when silver chloride is kept in sunlight, it decomposes into silver$\left(\mathrm{Ag}\right)$ and chlorine$\left({\mathrm{Cl}}_2\right)$. The white precipitate of silver chloride$\left(\mathrm{AgCl}\right)$ is turned to grey due to the formation of silver.

The balanced chemical reaction is written as,

$\mathbf{2}\mathbf{AgCl}\mathbf{\left(}\mathbf{ppt}\mathbf{\right)}\mathbf{}\stackrel{\mathbf{sunlight}}{\mathbf{\to }}\mathbf{}\mathbf{2}\mathbf{Ag}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{Cl}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}$

Hence, the reaction is a Decomposition reaction. It takes place under the sunlight and is also called a Photolytic decomposition reaction