Question

Describe the electrolytic refining method.

Answer 1

Part 1: The electrolytic refining method

• In the electrolytic refining method, the metals such as Copper, Aluminium, Silver, and Chromium are extracted and purified through the electrolytic process.
• In the electrolytic refining method. The impure metal acts as the anode. It is attached to the positive terminal of the battery.
• The pure metal acts as a cathode. It is attached to the negative terminal of the battery.
• Electrolyte is an aqueous solution of a suitable salt of the same metal.
• In this method, when an electric current is passed through the electrolyte, the pure metal deposits on the cathode and the impure metal dissolves from the anode into the solution or falls below the anode as anode mud.

Part 2: Example of the electrolytic refining

The electrolytic refining of Copper

• The thick block of impure Copper metal acts as the anode. It is attached to the positive terminal of the battery.
• The thin strip of pure Copper metal acts as the cathode. It is attached to the negative terminal of the battery.
• The electrolytic tank consists of acidified Copper sulphate solution as an electrolyte.
• In this method, when an electric current is passed through the electrolyte, the following reactions take at the two electrodes :
• At Cathode: The pure Copper metal deposits on the cathode.

$$\begin{gathered} {\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-}\to \mathrm{Cu}\left(\mathrm{s}\right) \\ \mathrm{Copper}\mathrm{Copper}\mathrm{atom} \\ \mathrm{ions} \end{gathered}$$

• At anode: The impure metal dissolves from the anode into the solution or falls below the anode as anode mud.

$$\begin{gathered} \mathrm{Cu}\left(\mathrm{s}\right)\to {\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-} \\ \mathrm{Copper}\mathrm{Copper}\mathrm{ions} \\ \mathrm{atoms} \end{gathered}$$