Extraction of Metals - Result Question 49
49. In the electrolysis of alumina, cryolite is added to
$(1986,1 M)$
(a) lower the melting point of alumina
(b) increase the electrical conductivity
(c) minimise the anode effect
(d) remove impurities from alumina
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Answer:
Correct Answer: 49. (a, b)
Solution:
- Alumina $\left(Al _2 O _3\right)$ has very high melting point and it is poor conductor of electricity. Both these factors posses difficulty in electrolysis of molten alumina.
Cryolite, $Na _3 AlF _6$, when mixed with alumina, lowers melting point as well as improve electrical conductivity, hence helps in electrolysis of $Al _2 O _3$.
BETA
