Cuyolite and fluorspar are mixed with `Al_(2)O_(3)` during electrolysis for extraction of aluminium to

Options

A. increase the mass of the reaction mixture
B. get other products at anode like fluorine
C. lower the melting point and increase the conductivity of the electrolyte
D. reduce aluminium oxide by cryolite

Answer

To solve the question regarding the use of cryolite (C₁₃Na₃AlF₆) and fluorspar (CaF₂) mixed with aluminum oxide (Al₂O₃) during the electrolysis for the extraction of aluminum, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components**:
- Cryolite (C₁₃Na₃AlF₆) and fluorspar (CaF₂) are both fluoride minerals.
- Aluminum oxide (Al₂O₃) is the primary ore from which aluminum is extracted.

2. **Purpose of Mixing**:
- The mixture of cryolite and fluorspar with aluminum oxide serves two main purposes:
- **Lowering the Melting Point**: Pure aluminum oxide has a high melting point (around 2050°C). The addition of cryolite and fluorspar reduces this melting point, making the electrolysis process more energy-efficient.
- **Increasing Conductivity**: The presence of cryolite and fluorspar enhances the conductivity of the electrolyte, which is crucial for efficient electrolysis. Higher conductivity allows for better flow of electric current through the molten mixture.

3. **Electrolysis Process**:
- During electrolysis, aluminum ions in the molten aluminum oxide are reduced to form aluminum metal at the cathode, while oxygen is released at the anode.
- The presence of cryolite and fluorspar aids in maintaining a stable and efficient electrolysis environment.

4. **Conclusion**:
- Therefore, the correct reason for mixing cryolite and fluorspar with aluminum oxide during the electrolysis for the extraction of aluminum is to **lower the melting point and increase the conductivity of the electrolyte**.

### Final Answer:
Cryolite and fluorspar are mixed with Al₂O₃ during electrolysis for the extraction of aluminum to lower the melting point and increase the conductivity of the electrolyte.

---