Question

Lead is not used for the preparation of hydrogen from acid give reason.

Answer 1

The following are the reasons

• Lead is not used in the preparation of hydrogen because lead reacts with dilute sulphuric or hydrochloric acid and forms an insoluble coating of lead sulfate or lead chloride.

$$\begin{gathered} \underset{\mathrm{Lead}}{\mathrm{Pb}\left(\mathrm{s}\right)}+\underset{\mathrm{Sulphuric}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)}\to \underset{\mathrm{Lead}\mathrm{sulphate}}{{\mathrm{PbSO}}_4\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)} \\ \underset{\mathrm{Lead}}{\mathrm{Pb}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}\mathrm{chloride}}{2\mathrm{HCl}\left(\mathrm{l}\right)}\to \underset{\mathrm{Lead}\mathrm{chloride}}{{\mathrm{PbCl}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)} \end{gathered}$$

• Lead is above hydrogen in the metal reactivity series. So it can displace hydrogen from compounds.
• The reactivity series of metals, also known as the activity series, refers to the arrangement of metals in the descending order of their reactivities.
• In the reactions of lead with acids, insoluble salts of lead are produced which forms a coating on pure lead and prevents the reaction from proceeding further.

Therefore, lead is not used for the preparation of hydrogen.