Answer
Metallic tin reduces $\mathrm{Sn}^{4+}$ to $\mathrm{Sn}^{2+}$as shown in the following spontaneous reaction:
$$\mathrm{Sn}^{4+}(\mathrm{aq})+\mathrm{Sn}(\mathrm{s}) \longrightarrow 2 \mathrm{Sn}^{2+}(\mathrm{aq})$$
$E_{\text {cell }}^{\circ}=0.154 \mathrm{V}-(-0.137 \mathrm{V})=0.017 \mathrm{V} .$
So, the presence of $\mathrm{Sn}(\mathrm{s})$ decreases the oxidation of $\mathrm{Sn}^{2+}(\mathrm{aq})$ to $\mathrm{Sn}^{4+}(\mathrm{aq})$.
Work Step by Step
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