Question

Cryolite, $N{a}_{3}Al{F}_6$ is added to $A{l}_2{O}_3$ in Hall-Heroult process to ____ m.p. and to ___________ electrical conductivity.

• A. higher, increase
• B. higher, decrease
• C. lower, increase
• D. lower, decrease

Answer 1

The correct option is C lower, increase

In the Hall–Héroult process alumina, $A{l}_2{O}_3$, is dissolved in molten cryolite, $N{a}_{3}Al{F}_6$ to lower it's melting point for easier electrolysis. It also increases conductivity of the solution.