Manipal MET2016ChemistryGeneral Principles and Processes of Isolation of Metals
Electrolytic reduction of alumina to aluminium by Hall-Heroult process is carried out
Options
- Ain the presence of NaCl
- Bin the presence of Hnorite
- Cin the presence of cryolite which forms a melt with lower melting temperature
- Din the presence of cryolite which forms a melt with higher melting temperature
Correct answer
C. in the presence of cryolite which forms a melt with lower melting temperature
Step-by-step solution
In the metallurgy of alumina, purified Al ₂ O ₃ is mixed with Na ₃ AlF ₆ or CaF ₂ which lowers the melting point of the mix and brings conductivity. 2 Al ₂ O ₃+3 C 4 Al +3 CO ₂