Write the formula of cryolite give its function in the extraction of aluminium?

The formula of cryolite is Na₃AlF₆, and its function in the extraction of aluminium is to lower the melting point of alumina and increase its electrical conductivity.

In the Hall–Héroult process of aluminium extraction, pure alumina (Al₂O₃) is dissolved in molten cryolite. This reduces the high melting point of alumina (about 2000°C) to around 950°C, making electrolysis easier and more efficient.

Composition

• Chemical formula: Na₃AlF₆
• Elements present: Sodium, Aluminium, Fluorine
• Type: Double fluoride of sodium and aluminium

Functions in Aluminium Extraction

1. Lowers the melting point of alumina.
2. Increases electrical conductivity of the molten mixture.
3. Acts as a solvent for alumina to maintain a stable bath during electrolysis.