Question

When $\mathrm{Zn}$ granules are added to dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$,which of the following reactions takes place?

• A. $\mathrm{Zn}$ gets oxidized
• B. $\mathrm{Zn}$ gets reduced
• C. $\mathrm{Zn}$ gets displaced
• D. $\mathrm{Zn}$ gets vaporized

Answer 1

The correct option is A

$\mathrm{Zn}$ gets oxidized

Explanation for the correct option:

1. When $\mathrm{Zn}$ (Zinc) granules are added to dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$, the following reaction takes place : $\underset{(\mathrm{Zinc}\mathrm{granuals})}{\underbrace{\mathrm{Zn}\left(\mathrm{s}\right)}}+\underset{(\mathrm{Sulphuric}\mathrm{acid})}{\underbrace{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}}\to \underset{(\mathrm{Zinc}\mathrm{sulphate})}{\underbrace{{\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)}}+\underset{(\mathrm{Hydrogen}\mathrm{gas})}{\underbrace{{\mathrm{H}}_2\left(\mathrm{g}\right)\uparrow }}$
2. Here, Zinc $\left(\mathrm{Zn}\right)$ reacts with dilute $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ to form Zinc sulphate( ${\mathrm{ZnSO}}_4$) and Hydrogen (${\mathrm{H}}_2$) gas.
3. In this reaction we can observe that $\mathrm{Zn}$ is oxidized to ${\mathrm{ZnSO}}_4$ , the oxidation state is increasing from $0\mathrm{to}+2.$
4. ${Zn}^0\to Z{n}^{+2}$ Increase in oxidation state, means oxidation.

Explanation for the incorrect options:

1. Zinc being more reactive than Hydrogen displaces it from the acid and forms Zinc sulphate and Hydrogen gas but $\mathrm{Zn}$ is not displaced, so option (C) is incorrect.
2. Zinc here is getting oxidized and not reduced so option (B) is incorrect.
3. The reaction here is exothermic, but the heat evolved is not sufficient to vaporize anything. so Zinc is not getting vaporized in this reaction. option (D) is incorrect.

Hence, option (A) is correct. i.e., when $\mathrm{Zn}$ granules are added to dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$, $\mathrm{Zn}$(Zinc) get oxidized.