Looking for classes? Ksquare Career Institute, Bengaluru →
Aluminium is extracted from alumina ($Al_2O_3$) by electrolysis of a molten mixture of:
A
$Al_2O_3 + KF + Na_3AlF_6$
B
$Al_2O_3 + HF + NaAlF_4$
C
$Al_2O_3 + CaF_2 + NaAlF_4$
D
$Al_2O_3 + Na_3AlF_6 + CaF_2$
Detailed Solution
In the Hall–Heroult process purified alumina is mixed with cryolite ($Na_3AlF_6$) and fluorspar ($CaF_2$).
These lower the melting point of the mixture and increase its conductivity.
So the molten mixture is $Al_2O_3 + Na_3AlF_6 + CaF_2$.
These lower the melting point of the mixture and increase its conductivity.
So the molten mixture is $Al_2O_3 + Na_3AlF_6 + CaF_2$.