Redox Reactions And Electrochemistry Ques 637
Question: $ Al_2O_3 $ is reduced by electrolysis at low potentials and high currents. If $ 4.0\times 10^{4} $ amperes of current is passed through molten $ Al_2O_3 $ for 6 hours, what mass of aluminium is produced- (Assume 100% current efficiency. At. mass of $ Al=27gmo{l^{-1}} $ )
Options:
A) $ 8.1\times 10^{4}g $
B) $ 2.4\times 10^{5}g $
C) $ 1.3\times 10^{4}g $
D) $ 9.0\times 10^{3}g $
Show Answer
Answer:
Correct Answer: A
Solution:
[a]
$ \therefore Q=i\times t $
$ \therefore Q=4.0\times 10^{4}\times 6\times 60\times 60C=8.64\times 10^{8}C $ Now since 96500 C liberates 9 g of Al $ 8.64\times 10^{8} $ C liberates $ \frac{9}{96500}\times 8.64\times 10^{8}g,Al=8.1\times 10^{4}g,of,Al $
