Standard entropy change calculations
a) Calculate the standard entropy change, delta S, for the reaction:

Fe2O3 (s) + 2 Al (s) =====> Al2O3 (s) + 2 Fe (s)

given that entropy S (Fe(s)) = 27.78 J/K mol, S (Al (s)) = 28.275 J/K mol,
S (Fe2O3 (s) = 87.4J/K mol, and S (Al2O3(s)) = 50.92 J/K mol

b) If delta H for the reaction is -851.5 kJ/mol at 25'C, calculate the standard free energy change, delta G for the reaction at 25'C.

c) Calculate the temperature at which the reaction changes from spontaneous to non-spontaneous.