Which of the following metals is present in the anode mud during electrolytic refining of copper ?

Question

Accepted Answer

During the electrolytic refining of copper, impurities present in the copper settle down as anode mud. The composition of this anode mud depends on the impurities present in the raw copper. Among the options provided, gold is the correct answer for the metal present in the anode mud during this process. Here's why:

1. **Gold (Option 2)**: Gold is often found in trace amounts in copper ores. During the electrolytic refining process, copper is dissolved from the anode and deposited on the cathode. However, gold, being less reactive and more noble than copper, does not dissolve in the electrolyte. Instead, it settles at the bottom of the electrolytic cell as part of the anode mud. This is why gold is present in the anode mud.

2. **Aluminium (Option 1)**: Aluminium is not typically found in copper ores and is not a common impurity in copper. Moreover, aluminium is more reactive than copper and would not remain in the anode mud. Instead, if present, it would dissolve in the electrolyte.

3. **Sodium (Option 3)**: Sodium is highly reactive and is not found as a metal in copper ores. It is not a typical impurity in copper and would not be present in the anode mud. Sodium, if present, would dissolve in the electrolyte due to its high reactivity.

4. **Zinc (Option 4)**: Zinc is more reactive than copper and, if present as an impurity, would dissolve in the electrolyte rather than settling as anode mud. Therefore, zinc is not found in the anode mud during the electrolytic refining of copper.

In conclusion, gold is the correct answer because it is a noble metal that does not dissolve in the electrolyte during the refining process, leading it to accumulate in the anode mud.