The Gibbs energy for the decomposition of `Al_(2)O_(3)` at `500^(@)C` is as follows:
`(2)/(3)Al_(2)O_(3) rarr (4)/(3)Al + O_(2), Delta_(r)G = +966kJ mol^(-1)`
The potential difference needed for electrolytic reeduction of `Al_(2)O_(3)` at `500^(@)C` is at least:

Options

A. 4.5 V
B. 3.0 V
C. 2.5 V
D. 5.0 V

Answer

C

Explanation

`Delta G =-n FE therefore E =(- Delta G)/(nF)`
`E=-(966xx10^(3))/(4xx96500)=-2.5 V`
`therefore` The potential difference needed for the reduction =2.5 V