Q. Aluminium is obtained by
A) Reducing $Al_{2}O_{3}$ with coke
B) Electrolysing $Al_{2}O_{3}$ dissolved in $Na_{3}AlF_{6}$
C) Reducing $Al_{2}O_{3}$ with chromium
D) Heating alumina with cryolite
Explanation
(b)
Aluminium is obtained by electrolysing alumina dissolved in cryolite $(Na_{3}AlF_{6})$
$\ \ \ \ \ \ \ \ \ 4Na_{3}AlF_{6} \rightleftharpoons 12\ Na^{+} + 4Al^{3 +} + 12F^{-}$
$\ 4Al^{3 +} + 12e^{-} \longrightarrow 4Al$ (at cathode)
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 12F^{-} \longrightarrow 6F_{2} + 12e^{-}$ (at anode)
$\ \ 2Al_{2}O_{3} + 6F_{2} \longrightarrow 4AlF_{3} + 3O_{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.