Question

Write a short note on the oxidising properties of nitric acid.

Answer 1

Oxidizing properties of nitric acid $\left({\mathrm{HNO}}_3\right)$:

• Concentrated nitric acid$\left({\mathrm{HNO}}_3\right)$ is a powerful oxidizing agent.
• When non-metals are treated with nitric acid, they get oxidized to their corresponding acids.

Example: Oxidation of sulphur to sulphuric acid

Balanced chemical reaction: $\underset{\mathrm{Sulphur}}{\mathrm{S}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitric}\mathrm{acid}}{6{\mathrm{HNO}}_3\left(\mathrm{l}\right)}\to \underset{\mathrm{Sulphuric}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Nitrogen}\mathrm{dioxide}}{6{\mathrm{NO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Example: Oxidation of phosphorous to phosphoric acid

Balanced chemical reaction: $\underset{\mathrm{Phosphorous}}{\mathrm{P}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitric}\mathrm{acid}}{5{\mathrm{HNO}}_3\left(\mathrm{l}\right)}\to \underset{\mathrm{Phosphoric}\mathrm{acid}}{{\mathrm{H}}_3{\mathrm{PO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Nitrogen}\mathrm{dioxide}}{5{\mathrm{NO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$