Gce Model Questions Vol1 2019 Chemistry Question 13

The metal oxide \(\mathrm{MO}\) has a standard enthalpy of formation \(\Delta H_f^\circ = -350\ \text{kJ mol}^{-1}\) and a standard entropy of formation \(\Delta S_f^\circ = -120\ \text{J K}^{-1}\text{mol}^{-1}\). Carbon monoxide has \(\Delta H_f^\circ = -110.5\ \text{kJ mol}^{-1}\) and \(\Delta S_f^\circ = 197\ \text{J K}^{-1}\text{mol}^{-1}\). The metal is extracted by the reduction reaction \(\mathrm{MO(s) + C(s) \rightarrow M(s) + CO(g)}\) carried out at 1 atm. (a) Calculate the minimum temperature at which the reduction becomes spontaneous (\(\Delta G < 0\)). (b) At \(1200\ \text{K}\) the equilibrium constant for the reaction is \(K = 5.0 \times 10^{-4}\). Assuming activities of solids are unity, calculate the equilibrium partial pressure of \(\mathrm{CO}\) at this temperature.