On the basis of the information available from the reaction $\frac{4}{3}\mathrm{Al}+{\mathrm{O}}_2\to \frac{2}{3}{\mathrm{Al}}_2{\mathrm{O}}_3;\mathrm{\Delta G}=-827\mathrm{kJ}/\mathrm{mol}\text{. The}$ minimum emf required to carry the electrolysis of $A{l}_2{O}_3$  is