Question

Name the acid used for the preparation of hydrogen chloride gas in the laboratory. Why is this particular acid preferred to other acids?

Answer 1

Acid used for the preparation of hydrogen chloride gas:

• Concentrated Sulphuric acid is used for the preparation of Hydrogen chloride$\left(\mathrm{HCl}\right)$ gas in the laboratory.
• Chemical Reaction:

$\underset{\mathrm{sodium}\mathrm{chloride}}{\mathrm{NaCl}\left(\mathrm{s}\right)}+\underset{\mathrm{sulphuric}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)}\to \underset{\mathrm{sodium}\mathrm{hydrogen}\mathrm{sulphate}}{{\mathrm{NaHSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}$

• The Hydrogen chloride gas is passed through a drying agent to remove moisture where concentrated sulphuric acid plays the role of dehydrating agent as well.

Hence, Concentrated Sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ is used for the preparation of Hydrogen chloride$\left(\mathrm{HCl}\right)$ gas in the laboratory.