JEE Main 2022 — General Principles and Processes of Isolation of Metals Question with Solution

Impure $\mathrm{Cu}$ obtained from ores is converted to pure $\mathrm{Cu}$ in an electrolyte cell that the impure copper as the anode an pure copper as the cathode. The electrolyte is an aqueous solution of ${\mathrm{CuSO}}_4$. At the impure $\mathrm{Cu}$ anode, $\mathrm{Cu}$ is oxidized along with the more easily oxidized metallic impurities such as $\mathrm{Zn}$ and Fe. The less easily oxidized impurities such as $\mathrm{Ag},\mathrm{Au}$, and $\mathrm{Pt}$ fall to the bottom of the cell as anode mud, which is reprocessed to recover the precious metals. At the pure $\mathrm{Cu}$ cathode, ${\mathrm{Cu}}^{2+}$ ions get reduced to pure copper metal

Anode (oxidation) : $\mathrm{M}\left(\mathrm{s}\right)⟶{\mathrm{M}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-}\left(\mathrm{M}=\mathrm{Cu},\mathrm{Zn},\mathrm{Fe}\right)$

Cathode (reduction) : ${\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-}⟶\mathrm{Cu}\left(\mathrm{s}\right)$

Thus, the net cell reaction simply involves transfer of $\mathrm{Cu}$ metal from the impure anode to the pure cathode, $\mathrm{Cu}$ obtained by this process is $99.95\%$ pure.