Question

In the purification of copper, a thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?

Answer 1

Electrolysis:-

• Electrolysis is actually a chemical process of for the production of electrical current for stimulating non-spontaneous reactions.
• The site where electrolysis occurs is in an electrolytic cell, which is actually a type of electrochemical cell used for the production of electrical current through a non-spontaneous reaction.
• Here, the positively charged electrode is known as anode whereas the negatively charged electrode is known as cathode.
• An impure copper metal is used as the anode, while the pure copper metal is used as the cathode.
• Copper $\left(\mathrm{Cu}\right)$ ion is positively charged and is attracted towards the plate that is connected to the negative terminal of the battery.
• Copper ions are transferred to the thin copper plate, and this thin pure copper plate must be further connected to the negative terminal of the battery.
• So, impure copper rod would be connected to the positive terminal of the battery.
• Reaction that takes place at the cathode:-

${\mathrm{Cu}}^{2+}+2{\mathrm{e}}^{-}\to \mathrm{Cu}(\mathrm{Reduction}\mathrm{of}\mathrm{Cu})$.

• Reaction that takes place at the anode:-

$\mathrm{Cu}\to {\mathrm{Cu}}^{2+}+2{\mathrm{e}}^{-}(\mathrm{oxidation}\mathrm{of}\mathrm{Cu})$.

• Diagram for the refining of copper:-