Under what condition can Al reduce MgO?

For a reaction to be feasible, the change in the Gibbs free energy of the reaction (\(\Delta G\)) must be negative. Lesser the ΔG, greater is the feasibility of the reaction. Above 1350°C, the standard Gibbs free energy of formation of Al₂O₃ from Al is less than that of MgO from Mg. Therefore, Al can reduce MgO above 1350°C.