In the extraction of aluminium by Hall-Heroult process, purified Al2O3 is mixed
with CaF2 to
(i) lower the melting point of Al2O3.
(ii) increase the conductivity of molten mixture.
(iii) reduce Al3+ into Al(s).
(iv) acts as catalyst.
NCERT Class XII
Chemistry - Exemplar Problems
Chapter 6. General Principles and Processes of Isolation of Elements