Question

Give reason for the following: Hydrogen chloride gas cannot be dried over quick lime.

Answer 1

• Quicklime is the common name for calcium oxide $\left(\mathrm{CaO}\right)$ which is basic in nature.
• Hydrogen chloride gas is strongly acidic in nature.
• If we are using calcium oxide $\left(\mathrm{CaO}\right)$for dying $\mathrm{HCl}$ gas then both react with each other to form salt and water. This reaction is called a neutralization reaction.

$\underset{\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Calcium}\mathrm{oxide}}{\mathrm{CaO}\left(\mathrm{s}\right)}\to \underset{\mathrm{Calcium}\mathrm{chloride}}{{\mathrm{CaCl}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

So, Quicklime is not used for dying $\mathbf{HCl}$ gas.