Extraction of Copper from Sulphide Ore - Reduction of Cu2O with Cu2S

Introduction:
The extraction of copper from sulphide ore involves several steps, including concentration, roasting, smelting, and refining. During the process, copper is obtained in its pure form by reduction of copper oxide with a suitable reducing agent. In this case, the reduction of Cu2O is achieved by using Cu2S as the reducing agent.

Explanation:

1. Concentration:
The first step in the extraction of copper from sulphide ore is concentration. The ore is crushed and ground into fine particles. Then, it is subjected to froth floatation, where certain chemicals are added to selectively separate copper sulphide minerals from other impurities.

2. Roasting:
After concentration, the copper sulphide ore is roasted in the presence of excess oxygen. This process converts copper sulphide (Cu2S) into copper oxide (Cu2O) and sulphur dioxide (SO2) gas. The reaction involved is as follows:
2Cu2S + 3O2 → 2Cu2O + 2SO2

3. Smelting:
The next step is smelting, where the copper oxide obtained from roasting is mixed with a flux (such as silica) and heated in a furnace. The flux helps to remove impurities and provides a suitable medium for the reduction reactions to occur.

4. Reduction of Cu2O:
During smelting, Cu2O is reduced to copper metal by using a suitable reducing agent. In this case, Cu2S acts as the reducing agent. The reaction involved is as follows:
Cu2O + Cu2S → 6Cu + SO2

Explanation of the Correct Answer:

The correct answer to the question is option 'C' - Cu2S. This is because Cu2S acts as the reducing agent, which reacts with copper oxide (Cu2O) to form copper metal (Cu) and sulphur dioxide (SO2) gas. The reaction can be represented as:
Cu2O + Cu2S → 6Cu + SO2

This process of reduction is an essential step in the extraction of copper from sulphide ore, as it helps to convert the copper oxide obtained from roasting into pure copper metal.

Conclusion:
In the extraction of copper from sulphide ore, Cu2S is used as the reducing agent to convert Cu2O into copper metal. This reduction reaction is an important step in the overall process of obtaining pure copper from its ore.