In the electrolytic refining of copper, which of the following is correct regarding the electrodes?

Question

Examoogle · Accepted Answer

The correct answer is Option C: Impure copper is the anode. In the electrolytic refining of copper, impure copper is used as the anode and a thin strip of pure copper is used as the cathode. During the process, copper ions from the impure anode dissolve into the electrolyte and deposit as pure copper on the cathode.

Step-by-Step Solution & Concepts:
In the electrolytic refining of copper, impure copper is used as the anode and a thin strip of pure copper is used as the cathode. During the process, copper ions from the impure anode dissolve into the electrolyte and deposit as pure copper on the cathode.

Working Principle: When current is passed through the electrolyte (acidified copper sulfate solution), copper atoms from the impure anode lose electrons to form $Cu^{2+}$ ions: $Cu \rightarrow Cu^{2+} + 2e^{-}$. These ions migrate to the cathode, where they gain electrons to become neutral copper atoms: $Cu^{2+} + 2e^{-} \rightarrow Cu$. Impurities less reactive than copper settle at the bottom as anode mud.

Key Formulas: $Cu \rightarrow Cu^{2+} + 2e^{-}$ — Oxidation at the Anode; $Cu^{2+} + 2e^{-} \rightarrow Cu$ — Reduction at the Cathode

Key Points: The electrolyte used is copper sulfate solution acidified with dilute sulfuric acid.; The anode is a thick block of impure copper.; The cathode is a thin strip of pure copper.; The impurities that are less reactive collect as anode mud below the anode.

Advantages: Produces highly pure copper (up to 99.99\%); Allows recovery of precious metals like gold and silver from anode mud

Disadvantages: High energy consumption due to electricity requirement; Requires careful disposal of acidic electrolyte waste

Applications: Production of high-conductivity copper wires for electrical circuits; Purification of base metals in metallurgical industries

Additional Info: The anode mud often contains valuable precious metals like silver, gold, and platinum.. Option A is wrong because the cathode must be pure to collect the refined metal.. Option B is wrong because the anode must be impure to donate metal ions to the solution.. Option D is wrong because the electrolyte is an acidic solution of copper sulfate, not a base.

Answer: C is correct — Impure copper is the anode, which serves as the source of metal ions during electrolysis.

Exam Tip: Remember that in ANY electrolytic refining process, the impure metal is ALWAYS placed at the Anode (Anode = Impure).

Examoogle · Answer

Option A: Impure copper is the cathode

Examoogle · Answer

Option B: Pure copper is the anode

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Option D: Electrolyte is a dilute base

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