Multiple choice

In the extraction of Al from Al2O3, which of the following is used?

  1. CaF2

  2. Na3AlF6

  3. CaCl2

  4. SiO2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Na3AlF6 (cryolite) is used in the Hall-Heroult process for aluminum extraction because it dissolves Al2O3 at much lower temperatures (≈1000°C) than pure Al2O3 would melt (>2000°C), making electrolysis feasible. CaF2 is used as a flux in steelmaking, CaCl2 is a drying agent, and SiO2 is a component of the cell lining but not the flux.

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