Free energies of formation ΔfG−of MgO(s) and CO(g) at 1273 K and 2273 K are given below:ΔfG∘MgO(s)=−941kJ/mol at 1273KΔfG⊙MgO(s)=−314kJ/mol at 2273KΔfG⊙CO(g)=−439kJ/mol at 1273KΔfG⊙CO(g)=−628kJ/mol at 2273KOn the basis of above data, The temperature at which carbon c1 be used as a reducing agent for MgO(s) is _______

Mg(s)+12O2(g)→MgO(s);ΔfG−=−941kJ/mol−1    . . . (1)C(s)+12O2(g)→4CO(g);ΔfG−=−439kJ/mol−1        . . . (2)The redox equation for reduction of MgO to Mg using C canbe obtained by subtracting Eq. (i) from Eq. (ii). Thus, MgO(s)+C(s)→Mg(s)+CO(g)Since ΔfG−of the above reduction ls *ve, reduction of MgO by C is not feasible at 1273 K.b. At 2273 KMg(s)+12O2(g)→MgO(s);ΔfG−=−314kJ/mol−1     . . . (3)C(s)+12O2(g)→CO(g);ΔfG−=−628kJ/mol−1         . . . .(4)Substracting Eq. (iii) from Eq. (iv), the redox equation isMgO(s)+C(s)→Mg(s)+CO(g) and ΔrG−=ΔfG−(products) −ΔfG−(reactants) =ΔHG−CO(g)−ΔfG−MgO(s)=(−628)−(−314)=−314kJmol−1Since ΔfG−for the above reduction is -ve, reduction of MgOby carbon at 2273 K is feasible.