Question

Name and explain the most widely used method for refining impure metals.

Answer 1

Method Name
The primary method for purifying metals is known as electrolytic refining or electrorefining.

Explanation of Electrolytic Refining
Electrolytic refining utilizes electrolysis to achieve metal purification. This process involves directing an electric current through an electrolyte (solution or molten) containing the impure metal. Consequently, pure metal is deposited at the cathode, while impurities are removed.

Process Details
1. The impure metal serves as the anode (positive electrode), and a pure sample of the metal being refined acts as the cathode (negative electrode).
2. The electrolyte is a solution or molten compound that contains ions of the metal undergoing purification.
3. Upon current passage, metal ions from the impure anode dissolve into the electrolyte and migrate towards the cathode.
4. Pure metal deposits onto the cathode. Impurities insoluble in the electrolyte either remain at the anode or accumulate as anode mud at the cell's base.

Example: Copper Refining
The purification of copper is a typical application:
- Anode: Impure copper
- Cathode: Pure copper
- Electrolyte: Copper sulfate solution (\( \text{CuSO}_4 \))
During this process, pure copper plates onto the cathode. Impurities like iron, nickel, and zinc are either left at the anode or settle as sludge.

Advantages of Electrolytic Refining
- Enables the extraction of highly pure metal from impure sources.
- Applicable to a diverse range of metals, including copper, aluminum, and gold.
- Offers efficiency, yielding high-purity metals suitable for industrial applications.