Aluminium is extracted from alumina \left ( Al_{2}O_{3} \right )  by electrolysis of a molten mixture of:

  • Option 1)

    Al_{2}O_{3}+HF+N_{a}AlF_{4}

  • Option 2)

    Al_{2}O_{3}+CaF_{2}+N_{a}AlF_{4}

  • Option 3)

    Al_{2}O_{3}+Na_{3}AlF_{6}+CaF_{2}

  • Option 4)

    Al_{2}O_{3}+KF+Na_{3}AlF_{6}

 

Answers (1)
V Vakul

As we learnt in concept

Hall and Heroult Process -

Use to extract aluminium. A fuse mixture of alumina (20%), cryolite (60%) and fluorspar (20%) is electrolysed using carbon electrodes.

- wherein

Cryolite makes Al2O3 conducting, fluorspar decreases the melting point of alumina

 

 In Hall Heroult process, a fused mixture of alumina (20%) Al2O3, cryalite (60%) Na3AlF6, and flourspar (20%) CaF2 is electrolysed using carbon electrodes Al_{2}O_{3}+Na_{3}AIF_{6}+CaF_{2}

 

alumina           cryalite              flourspar


Option 1)

Al_{2}O_{3}+HF+N_{a}AlF_{4}

This solution is incorrect 

Option 2)

Al_{2}O_{3}+CaF_{2}+N_{a}AlF_{4}

This solution is incorrect 

Option 3)

Al_{2}O_{3}+Na_{3}AlF_{6}+CaF_{2}

This solution is correct 

Option 4)

Al_{2}O_{3}+KF+Na_{3}AlF_{6}

This solution is incorrect 

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