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The Gibbs energy for the decomposition o...

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 reduction of `Al_(2)O_(3)` at `500^(@)C` is at least:

A

(4.5V)

B

`(3.0V)`

C

`(2.5V)`

D

`5.0V)`

Text Solution

Verified by Experts

`2/3A1_2o_3to4/3a1+o_2`
Thus,`2/3xx3(o^(2-))`
i.e `2o^(2-)to0_2+4e^(-)[Qn=4]`
`Delta G -+966 kJm oI^(-1)=996xx10^(3)Jm oI^(-1) Q DeltaG=nFE_(cell)`
`implies 996xx10^(-3)=-4xx96500xxE_(cell) implies E_(cell)=2.5V`
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