Question
Chemistry Question on Thermodynamics
The Gibbs' energy for the decomposition of Al2O3 at 500∘C is as follows: 32Al2O3−>34Al+O2;ΔrG=+960kJmol−1 The potential difference needed for the electrolytic reduction of aluminium oxide (Al2O3) at 500∘C is at least
A
3.0V
B
2.5V
C
5.0V
D
4.5V
Answer
2.5V
Explanation
Solution
ΔG∘=−nFE∘ 960×1000=−4×96500×E∘ E∘=−2.48V So difference = 2.5V