Question

When Lead nitrate is heated it decomposes with a cracking sound, a reddish brown gas is liberated and a solid residue is left in the test tube. Write the balanced chemical equation to describe the changes on decomposition of Lead nitrate.

Answer 1

1. Decomposition reaction

In a decomposition reaction, the reactant compound is broken down into more than one smaller compound.

2. Decomposition reaction of Lead nitrate

A solid residue $\left(\mathrm{PbO}\right)$ and a reddish-brown gas $\left({\mathrm{NO}}_2\right)$ are formed when Lead nitrate $\left[\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\right]$ undergoes a decomposition reaction. The chemical reaction is given below:

$\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)\to \mathrm{PbO}\left(\mathrm{s}\right)+{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$
3. Balanced equation

In order to balance the given reaction, two is used as a coefficient for Lead nitrate and Lead oxide whereas four is used as a coefficient for Nitrogen dioxide.

The balanced chemical equation for the decomposition of Lead nitrate is shown below.

$$\begin{gathered} 2\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)\to 2\mathrm{PbO}\left(\mathrm{s}\right)+4{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right) \\ \left(\mathrm{Lead}\mathrm{nitrate}\right)\left(\mathrm{Lead}\mathrm{oxide}\right)\left(\mathrm{Nitrogen}\mathrm{dioxide}\right)\left(\mathrm{Oxygen}\right) \end{gathered}$$