Question

_____ acid is a strong oxidizing agent and so it is not used in the preparation of hydrogen.

Answer 1

Nitric acid (${\mathrm{HNO}}_3$) is a strong oxidizing agent and so it oxidizes hydrogen gas produced into water.

Hydrochloric acid or sulphuric acid are preferred because they do not oxidize hydrogen formed into water and so hydrogen gas formed can be collected over water.

Laboratory preparation of hydrogen.

Hydrogen is prepared in the laboratory by the action of dilute hydrochloric acid ($\mathrm{HCl}$) or dilute sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$) on zinc granules$$\begin{gathered} \mathrm{Zn}+2\mathrm{HCl}\to {\mathrm{ZnCl}}_2+{\mathrm{H}}_2 \\ \mathrm{Zinc}\mathrm{Hydrochlloric}\mathrm{acid}\mathrm{Zinc}\mathrm{chloride}\mathrm{Hydrogen}\mathrm{gas} \\ \mathrm{Zn}+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{ZnSO}}_4+{{\mathrm{H}}_2}_{} \\ \mathrm{Zinc}\mathrm{Sulphuric}\mathrm{acid}\mathrm{Zinc}\mathrm{sulphate}\mathrm{Hydrogen}\mathrm{gas} \end{gathered}$$

• Zinc granules are preferred over pure zinc because zinc granules contain the impurity of copper, which acts as a catalyst and increases the rate of reaction.
• Nitric acid (${\mathrm{HNO}}_3$) is a strong oxidizing agent and so it oxidizes hydrogen gas produced into water.
• Hydrochloric acid or sulphuric acid are preferred because they do not oxidize hydrogen formed in water and so hydrogen gas formed can be collected over water.

Therefore and dilute hydrochloric acid($\mathrm{HCl}$) and dilute sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$) are used as reactants in the laboratory preparation of hydrogen.

Hence dilute nitric acid is a strong oxidizing agent and so it is not used in the preparation of hydrogen.