Question

Which property of sulphuric acid is made use of in the following:

1. Liberation of Sulphur from ${\mathrm{H}}_2\mathrm{S}$ with concentrated form
2. Charring of sugar with hot concentrated acid
3. Liberation of Carbon Monoxide from hot concentrated acid.

Answer 1

Liberation of Sulphur from ${\mathrm{H}}_2\mathrm{S}$ with concentrated form :

1. $$\begin{gathered} {\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{S}\left(\mathrm{aq}\right)\to {\mathrm{SO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+\mathrm{S}\left(\mathrm{s}\right) \\ \mathrm{conc}.\mathrm{Sulphuric}\mathrm{acid}+\mathrm{Hydrogen}\mathrm{Sulphide}\to \mathrm{Sulphur}\mathrm{dioxide}+\mathrm{Water}+\mathrm{Sulphur} \end{gathered}$$
2. ${\mathrm{H}}_2{\mathrm{SO}}_4$ act as an oxidizing agent.

Charring of sugar with hot concentrated acid

1. It is done to remove the water from the sugar.
2. So ${\mathrm{H}}_2{\mathrm{SO}}_4$ act as a dehydrating agent.

Liberation of carbon monoxide from hot concentrated acid:

1. $$\begin{gathered} \mathrm{HCOOH}\left(\mathrm{aq}\right)\stackrel{\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }\mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{Formic}\mathrm{acid}\mathrm{Carbon}\mathrm{Monoxide}+\mathrm{Water} \end{gathered}$$
2. ${\mathrm{H}}_2{\mathrm{SO}}_4$acts as a dehydrating agent.

Hence,

1. $\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4$ acts as an oxidizing agent in the liberation of $\mathrm{S}$ from ${\mathrm{SO}}_2$
2. $\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4$ acts as a dehydrating agent in charring of sugar
3. $\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4$ acts as a dehydrating agent in the liberation of $\mathrm{CO}$ from $\mathrm{HCOOH}$.