Which of the following methods is used for refining impure metals? 

The correct answer is Electrolytic refining.

Key Points

• Electrolytic refining is a method used to purify impure metals by using electrolysis.
• In this process, the impure metal is made the anode, and a pure metal strip is made the cathode.
• An electrolyte solution containing the metal ions is used to facilitate the transfer of metal ions from the anode to the cathode.
• As a result, the pure metal is deposited on the cathode, while impurities either fall off as anode mud or remain in the solution.
• This method is commonly used for refining metals like copper, nickel, lead, and zinc.

Additional Information

• Electrolysis is the process of using an electric current to drive a non-spontaneous chemical reaction.
• In electrolytic refining, the energy supplied by the electric current helps in the separation of pure metal from its impurities.
• Anode refers to the electrode where oxidation occurs, while the cathode refers to the electrode where reduction occurs.
• Anode mud is the insoluble impurities that collect at the bottom of the electrolytic cell during the refining process.
• This method ensures high purity levels of the refined metal, often exceeding 99.9% purity.