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Enthalpy of Reaction
[2ΔHf(Fe2O3 (s hematite))] - [4ΔHf(Fe (s alpha)) + 3ΔHf(O2 (g))]
[2(-824.25)] - [4(0) + 3(0)] = -1648.5 kJ
-1,648.50 kJ (exothermic)
[2ΔSf(Fe2O3 (s hematite))] - [4ΔSf(Fe (s alpha)) + 3ΔSf(O2 (g))]
[2(87.4)] - [4(27.28) + 3(205.03)] = -549.41 J/K
-549.41 J/K (decrease in entropy)
Free Energy of Reaction (at 298.15 K)
From ΔGf° values:
[2ΔGf(Fe2O3 (s hematite))] - [4ΔGf(Fe (s alpha)) + 3ΔGf(O2 (g))]
[2(-742.24)] - [4(0) + 3(0)] = -1484.48 kJ
-1,484.48 kJ (spontaneous)
From ΔG = ΔH - TΔS:
-1484.69 kJ (spontaneous)
Equilibrium Constant, K (at 298.15 K)
This process is favorable at 25°C.
Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 77.
Kotz, John C. and Treichel, Paul. Chemistry & Chemical Reactivity 4th ed.; Thomson Brooks/Cole: Belmont, CA, 1999; pp 149, 151.
Zumdahl, Steven and Zumdahl, Susan A. Chemistry 9th ed.; Brooks/Cole: Belmont, CA, 2014; p 131.