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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:A. 2.5VB. 5.0VC. 4.5VD. 3.0V |
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Answer» Correct Answer - A `2//3Al_(2)O_(3)rarr4//3Al+O_(2)`. `DeltaG= +966kJ "mol"^(-1)` `4//3Al^(3+)+4e^(-)rarr4//3Al` `DeltaG=-nFE` ` therefore 966 xx10^(3)=-4xx96500xxE`. `therefore E=2.50V` `therefore` the minimum potential difference required = 2.50V. |
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