MCQ
Aluminium is obtained by
- AReducing $A{l_2}{O_3}$ with coke
- ✓Electrolysing $A{l_2}{O_3}$ dissolved in $N{a_3}Al{F_6}$
- CReducing $A{l_2}{O_3}$ with chromium
- DHeating alumina and cryolite
✓
Answer
Correct option: B.
Electrolysing $A{l_2}{O_3}$ dissolved in $N{a_3}Al{F_6}$
b
Aluminium is obtained by electrolising alumina dissolved in cryolite $\left( Na _3 AlF _6\right)$
Aluminium is obtained by electrolising alumina dissolved in cryolite $\left( Na _3 AlF _6\right)$
$4 Na _3 AlF _6 \leftrightharpoons 12 Na ^{+}+4 Al ^{3+}+12 F ^{-}$
$4 Al ^{3+}+12 e ^{-} \rightarrow 4 Al \text { (at cathode) }$
$12 F ^{-} \rightarrow 6 F _2+12 e ^{-} \text {(at anode) }$
$2 Al _2 O _3+6 F _2 \rightarrow AlF _3+3 O _2$
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