The standard reduction potentials of $2 \mathrm{H}^{+} / \mathrm{H}_2, \mathrm{Cu}^{2+} / \mathrm{Cu}$,…
The standard reduction potentials of $2 \mathrm{H}^{+} / \mathrm{H}_2, \mathrm{Cu}^{2+} / \mathrm{Cu}$, $\mathrm{Zn}^{2+} / \mathrm{Zn}$ and $\mathrm{NO}_3^{-}, \mathrm{H}^{+} / \mathrm{NO}$ are $0.0,0.34,-0.76$ and 0.97 V pespectively. Identify the correct statements from the following
I. $\mathrm{H}^{+}$does not oxidize Cu to $\mathrm{Cu}^{2+}$
II. Zn reduces $\mathrm{Cn}^{2+}$ to Cu
III. $\mathrm{NO}_3^{-}$oxidizes Cu to $\mathrm{Cu}^{2+}$
I, II only
I, II, III
I, III only
II, III only
Solution
The greater the negative value of the reduction potential value in the electrochemical series, the greater will be the tendency to act as a reducing agent it mean it can reduce other element whose value is high.
\begin{array}{ll}\mathrm{Zn}^{2+} / \mathrm{Zn} & -0.76 V \\2 \mathrm{H}^{+} / \mathrm{H}_2 & 0 V \\\mathrm{Cu}^{2+} / \mathrm{Cu} & 0.34 V \\\mathrm{NO}_3^{-} / \mathrm{H}^{+} / \mathrm{NO} & 0.97 V\end{array}
Zinc acts as a good reducing agent than copper. This implies that zinc can reduce copper.
$2 \mathrm{H}^{+} / \mathrm{H}_2$ cannot oxides $\mathrm{Cu} / \mathrm{Cu}^{2+}$ because it have lower reduction potential then copper.
$\mathrm{NO}_3^{-}$have high reduction potential, it can oxides copper.