Free Energy and Temperature
2 Fe2O3(s) + 3 C(s) ? 4 Fe(s) + 3 CO2(g)
DHorxn = +467.9 kJ DSorxn = +560.3 J/K
DGorxn = 467.9 kJ - (298K)(0.560kJ/K) = +300.8 kJ
Reaction is reactant-favored at 298 K
At what T does DGorxn just change from (+) to (-)?
i.e. what is T for DGorxn = 0 = DHorxn - TDSorxn
If DGorxn = 0 then DHorxn = TDSorxn
so T = DHo/DSo ~ 468kJ/0.56kJ/K = 836 K or 563oC