question_answer

Aluminium oxide may be electrolysed at \[1000{}^\circ C\]to furnish aluminium metal (Atomic mass\[=27u;\] 1 Faraday = 96500. The cathode reaction is \[A{{l}^{3+}}+3{{e}^{-}}\to A{{l}^{0}}\] To prepare 5.12 kg of aluminium metal by this method would require     AIEEE  Solved  Paper-2005

A) \[5.49\times {{10}^{1}}C\]of electricity

B) \[5.49\times {{10}^{4}}C\]of electricity

C) \[1.83\times {{10}^{7}}C\]of electricity

D) \[5.49\times {{10}^{7}}C\]of electricity

Correct Answer: D

Solution :

The mass of any substance liberated at the electrode is directly proportional to the quantity of electricity passed. Thus, calculate the amount of electricity (Q) by the formula \[\omega =zQ\] where, amount of metal electrochemical equivalent