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Enthalpy of Reaction
[2ΔHf(Fe2O3 (s hematite))] - [4ΔHf(FeO (s)) + 1ΔHf(O2 (g))]
[2(-824.25)] - [4(-271.96) + 1(0)] = -560.66 kJ
-560.66 kJ (exothermic)
[2ΔSf(Fe2O3 (s hematite))] - [4ΔSf(FeO (s)) + 1ΔSf(O2 (g))]
[2(87.4)] - [4(60.75) + 1(205.03)] = -273.23 J/K
-273.23 J/K (decrease in entropy)
Free Energy of Reaction (at 298.15 K)
From ΔGf° values:
[2ΔGf(Fe2O3 (s hematite))] - [4ΔGf(FeO (s)) + 1ΔGf(O2 (g))]
[2(-742.24)] - [4(-251.46) + 1(0)] = -478.64 kJ
-478.64 kJ (spontaneous)
From ΔG = ΔH - TΔS:
-479.20 kJ (spontaneous)
Equilibrium Constant, K (at 298.15 K)
This process is favorable at 25°C.
Zumdahl, Steven and Zumdahl, Susan A. Chemistry 9th ed.; Brooks/Cole: Belmont, CA, 2014; p 131.