Question

Identify the type of reaction taking place in the following cases and write the balanced chemical equation for the reaction.

Potassium iodide reacts with lead nitrate to produce Potassium nitrate and Lead iodide.

Answer 1

Double displacement reaction:

The chemical reaction in which one component each of both the reacting molecules is exchanged to form the products is called a Double displacement reaction.

For example:

When Calcium hydroxide$(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2)$ is bubbled with Carbon dioxide$\left({\mathrm{CO}}_2\right)$ it produces Calcium carbonate$\left({\mathrm{CaCO}}_3\right)$ and Water.

$\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)\to {\mathrm{CaCO}}_3\left(\mathrm{ppt}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

When Potassium iodide$\left(\mathrm{KI}\right)$ reacts with Lead nitrate$(\mathrm{Pb}\left({\mathrm{NO}}_3\right))$ and produces Potassium nitrate$\left({\mathrm{KNO}}_3\right)$ and Lead iodide$\left({\mathrm{PbI}}_2\right)$.

$\mathbf{2}\mathbf{KI}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{Pb}{\mathbf{\left(}{\mathbf{NO}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{2}}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\stackrel{\mathbf{heat}\mathbf{}}{\mathbf{\to }}\mathbf{}{\mathbf{PbI}}_{\mathbf{2}}\mathbf{\left(}\mathbf{ppt}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{2}{\mathbf{KNO}}_{\mathbf{3}}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}$

Hence, it is a double displacement reaction.