On the basis of information available for the reaction $\frac{4}{3}\mathrm{Al}+{\mathrm{O}}_2\to \frac{2}{3}{\mathrm{Al}}_2{\mathrm{O}}_3$, $\mathrm{\Delta G}=-827 \mathrm{kJ}/\mathrm{mol}$ of O₂, the minimum emf required to carry out an electrolysis of Al₂O₃ is