Extraction of copper by smelting uses silica as an additive to
remove:

Options

A. `Cu_(2)O`
B. `FeO`
C. `Cu_(2)S`
D. `FeS`

Answer

To solve the question regarding the extraction of copper by smelting and the role of silica as an additive, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Extraction Process**:
- The extraction of copper primarily involves the smelting of copper ores, which are often found in the form of sulfides, such as chalcopyrite (CuFeS₂).

2. **Roasting of Copper Ore**:
- The first step in the extraction process is roasting the copper sulfide ore. This process converts the sulfide minerals into oxides. The general reaction can be represented as:
\[ 2CuFeS_2 + 5O_2 \rightarrow 2Cu_2S + 2FeS + 2SO_2 \]
- Here, copper(I) sulfide (Cu₂S) and iron(II) sulfide (FeS) are formed.

3. **Formation of Iron Oxide**:
- The iron sulfide (FeS) is further oxidized to iron oxide (FeO) during the smelting process:
\[ 2FeS + 3O_2 \rightarrow 2FeO + 2SO_2 \]

4. **Role of Silica**:
- Silica (SiO₂) is added as a flux during the smelting process. The purpose of adding silica is to combine with the iron oxide (FeO) to form a slag, which is a waste product that can be removed from the furnace. The reaction can be represented as:
\[ FeO + SiO_2 \rightarrow FeSiO_3 \text{ (slag)} \]
- This slag (FeSiO₃) is less dense than the molten metal and can be easily separated.

5. **Conclusion**:
- Therefore, the addition of silica during the smelting of copper is specifically to remove iron oxide (FeO) from the mixture, allowing for the efficient extraction of copper.

### Final Answer:
Silica is added during the extraction of copper by smelting to remove iron oxide (FeO).

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