Mention the role of cryolite in the extraction of aluminium.

Answer

### Step-by-Step Solution

1. **Definition of Cryolite**: Cryolite is a mineral composed of sodium aluminum fluoride (Na3AlF6). It is used in the extraction of aluminum primarily in the Hall-Héroult process.

2. **Role as a Solvent**: In the extraction process, cryolite acts as a solvent for aluminum oxide (Al2O3). When aluminum oxide is mixed with molten cryolite, it helps in dissolving the aluminum oxide, making it easier to extract aluminum.

3. **Lowering Melting Point**: One of the significant roles of cryolite is to lower the melting point of aluminum oxide. Pure aluminum oxide has a melting point of about 2000 to 2500 degrees Celsius. However, when mixed with cryolite, the melting point is reduced to approximately 900 to 1000 degrees Celsius. This reduction in melting point makes the extraction process more energy-efficient.

4. **Increasing Electrical Conductivity**: Cryolite also plays a crucial role in increasing the electrical conductivity of the molten mixture. Higher conductivity allows for more efficient electrolysis during the extraction of aluminum, which is essential for the Hall-Héroult process.

5. **Economic Benefits**: By lowering the melting point and increasing conductivity, cryolite makes the extraction of aluminum more economical. It reduces energy consumption and operational costs during the aluminum extraction process.

### Summary of the Role of Cryolite:
- Acts as a solvent for aluminum oxide.
- Lowers the melting point of aluminum oxide, making extraction easier.
- Increases electrical conductivity of the molten mixture.
- Enhances the overall economic efficiency of the aluminum extraction process.