Redox Reactions And Electrochemistry Ques 93

Question: Aluminium oxide may be electrolysed at 1000°C to furnish aluminium metal (At. Mass = 27 amu; 1 Faraday = 96,500 Coulombs). The cathode reaction is $ Al^{3}+3{e^{-}}\to Al{}^\circ $ To prepare 5.12kg of aluminium metal by this method would require [AIEEE 2005]

Options:

A) $ 5.49\times 10^{7}C $ of electricity

B) $ 1.83\times 10^{7}C $ of electricity

C) $ 5.49\times 10^{4}C $ of electricity

D) $ 5.49\times 10^{1}C $ of electricity

Show Answer

Answer:

Correct Answer: A

Solution:

27 gm of Al is obtained by passing a current of 3 × 96500 C.

$ \because $ 1 gm of Al is obtained by passing a current of $ 3\times \frac{96500}{27}C. $ \ 5.12 × 103 gm of Al is obtained by passing a current of $ 3\times \frac{96500}{27}\times 5.12\times 1000 $ = 1.83 × 107 C × 3 = 5.49 × 107C.



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