In the extraction of aluminium by Hall-Heroult process, purified Al2O3 is mixed with CaF2 to
In the extraction of aluminium by Hall-Heroult process, purified Al2O3 is mixed with CaF2 to
The correct option is D increase the conductivity of molten mixture.
In the Hall-Heroult smelting process, a nearly pure aluminium oxide compound called alumina is dissolved at 950 °C (1750 °F) in a molten electrolyte composed of aluminium, sodium and fluorine. This is electrolyzed to give aluminium metal at the cathode and oxygen gas at the anode.
Option (A):
The addition of CaF2 lowers the melting point of Al2O3 from 2072 °C to 950 °C and so it can easily melt . CaF2 also increases the conductivity of molten mixture.
Option (B):
CaF2 is mixed with Al2O3 to increase the conductivity of molten mixture.
Option (C):
CaF2 cannot reduce Al3+ into Al(s).
Option (D):
CaF2 does not act as a catalyst.
So, the correct options are (A) and (B)
increase the conductivity of molten mixture.
In the Hall-Heroult smelting process, a nearly pure aluminium oxide compound called alumina is dissolved at 950 °C (1750 °F) in a molten electrolyte composed of aluminium, sodium and fluorine. This is electrolyzed to give aluminium metal at the cathode and oxygen gas at the anode.
Option (A):
The addition of CaF2 lowers the melting point of Al2O3 from 2072 °C to 950 °C and so it can easily melt . CaF2 also increases the conductivity of molten mixture.
Option (B):
CaF2 is mixed with Al2O3 to increase the conductivity of molten mixture.
Option (C):
CaF2 cannot reduce Al3+ into Al(s).
Option (D):
CaF2 does not act as a catalyst.
So, the correct options are (A) and (B)
