Neco 2020 Chemistry Question 41

A metal M forms the oxide \(\text{M}_2\text{O}_3\) with a standard enthalpy of formation \(\Delta H_f^\circ = -1200 \text{ kJ mol}^{-1}\). The oxide is reduced by carbon according to \(\text{M}_2\text{O}_3 + 3\text{C} \rightarrow 2\text{M} + 3\text{CO}\). The standard entropy change for the reaction is \(\Delta S^\circ = +200 \text{ J K}^{-1}\text{mol}^{-1}\). The standard enthalpy of formation of CO(g) is \(-110.5 \text{ kJ mol}^{-1}\). (a) Calculate the standard enthalpy change \(\Delta H^\circ\) for the reduction. (b) Determine the Gibbs free energy change \(\Delta G^\circ\) at \(1500 \text{ K}\) and state whether the reduction is spontaneous. (c) Find the minimum temperature at which the reduction becomes spontaneous (i.e., \(\Delta G^\circ =0\)).