Question:medium

In the electrolysis of alumina to obtain aluminium metal, cryolite is added mainly to:

Updated On: Mar 27, 2026
  • Lower the melting point of alumina
  • Dissolve the alumina in molten cryolite
  • Remove impurities from alumina
  • Increase electrical conductivity
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The Correct Option is A

Solution and Explanation

Cryolite (Na3AlF6) is essential in the electrolytic extraction of aluminum from alumina (Al2O3) due to the following reasons:

1. Melting Point Reduction: Alumina's melting point of approximately 2072°C is drastically reduced to 900°C - 1000°C by the addition of cryolite, improving energy efficiency and cost-effectiveness.

2. Solution Formation: Beyond lowering the melting point, cryolite functions as a solvent for alumina. This dissolution forms a conductive liquid mixture, crucial for effective electrolysis.

3. Electrical Conductivity: The presence of cryolite boosts the solution's electrical conductivity, ensuring efficient current flow for aluminum extraction.

4. Primary Function: The main justification for including cryolite is its ability to "Lower the melting point of alumina."

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