Question

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

Answer 1

Step 1: Name of the method
The most widely used method for refining impure metals is called electrolytic refining or electrorefining.

Step 2: Explanation of electrolytic refining
Electrolytic refining is a process that uses electrolysis to purify metals. It involves passing an electric current through a solution or molten electrolyte containing the impure metal, resulting in the deposition of pure metal at the cathode and the removal of impurities.

Step 3: Process details
1. The impure metal is made the anode (positive electrode), and a pure metal (the metal being refined) is made the cathode (negative electrode).
2. The electrolyte used in the process is a solution or molten compound that contains the metal ions of the metal being purified.
3. As the current passes through the electrolyte, metal ions from the impure metal dissolve into the solution at the anode and move toward the cathode.
4. The metal ions then deposit as pure metal at the cathode, while impurities that do not dissolve in the electrolyte either remain at the anode or fall to the bottom of the electrolytic cell as anode mud.

Step 4: Example of electrolytic refining
A common example of electrolytic refining is the refining of copper. In this case:
- The anode is made of impure copper.
- The cathode is made of pure copper.
- The electrolyte is a copper sulfate solution (\( \text{CuSO}_4 \)).
During the process, pure copper is deposited at the cathode, and impurities such as iron, nickel, and zinc are either left behind at the anode or fall to the bottom as sludge.

Step 5: Advantages of electrolytic refining
- It allows the extraction of pure metal from impure samples.
- It can be used for a wide range of metals, including copper, aluminum, and gold.
- It is efficient and can produce high-purity metals suitable for industrial applications.