Purification And Characterisation Of Organic Compounds Question 9
Question: In the electrolysis of alumina to obtain aluminiumb metal, cryolite is added mainly to
Options:
A) lower the melting point of alumina
B) dissolve alumina in molten cryolite
C) remove the impurities of alumina
D) increase the electrical conductivity
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Fused alumina $ (Al_2O_3) $ is a bad conductor of electricity.
Therefore, cryolite $ (Na_3AlF_6) $ and fluorspar $ (CaF_2) $ are added to purified alumina which not only make alumina a good conductor of electricity but also reduce the melting point of the mixture to around 1140 K.
BETA
