Question

Concentrated sulphuric acid is both an oxidizing agent and a non-volatile acid. Write one equation each to illustrate the above-mentioned properties of sulphuric acid.

Answer 1

Concentrated sulphuric acid $(\mathrm{Conc}.{\mathrm{H}}_2{\mathrm{SO}}_4)$ can act as both oxidizing agent and a non-volatile acid.

• The given below reaction shows the non-volatile property of $\mathrm{Conc}.{\mathrm{H}}_2{\mathrm{SO}}_4$.

$\underset{(\mathrm{Sodium}\mathrm{chloride})}{\underbrace{\mathrm{NaCl}\left(\mathrm{s}\right)}}+\underset{(\mathrm{Sulphuric}\mathrm{acid})}{\underbrace{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)}}\underset{}{\to }\underset{(\mathrm{Sulphuric}\mathrm{bisulphate})}{\underbrace{{\mathrm{NaHSO}}_4\left(\mathrm{s}\right)}}+\underset{(\mathrm{Hydrochloric}\mathrm{acid})}{\underbrace{\mathrm{HCl}(\mathrm{aq}.)}}$

Here, in this reaction, sodium chloride is reacting with sulphuric acid and giving sodium bisulphate and hydrochloric acid.

• The below-given reaction shows the oxidizing property of $\mathrm{Conc}.{\mathrm{H}}_2{\mathrm{SO}}_4$

$\underset{\left(\mathrm{Carbon}\right)}{\underbrace{\mathrm{C}\left(\mathrm{s}\right)}}+\underset{(\mathrm{Sulphuric}\mathrm{acid})}{\underbrace{2{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)}}\underset{}{\to }\underset{(\mathrm{Carbon}\mathrm{dioxide})}{\underbrace{{\mathrm{CO}}_2\left(\mathrm{g}\right)}}+\underset{\left(\mathrm{Water}\right)}{\underbrace{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}}+\underset{(\mathrm{Sulphur}\mathrm{dioxide})}{\underbrace{2{\mathrm{SO}}_2\left(\mathrm{g}\right)}}$

Here in this reaction, carbon is reacting with sulphuric acid and giving carbon dioxide, water, and sulphur dioxide gas is evolved.

From the above discussion, we can conclude that:-

• Sulphuric acid can act as a non-volatile acid. This is because sulphuric acid has high boiling points and this property makes this acid to act as a non-volatile acid.
• Sulphuric acid can act as an oxidizing agent. This is due to the fact on thermal decomposition it yields nascent oxygen $\left[\mathrm{O}\right]$.

$$\begin{gathered} {\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{SO}}_2\left(\mathrm{g}\right)+\left[\mathrm{O}\right] \\ (\mathrm{sulphuric}(\mathrm{water})(\mathrm{sulphur}(\mathrm{nascent} \\ \mathrm{acid})\mathrm{dioxide})\mathrm{oxygen}) \end{gathered}$$