Example: thermodynamic properties and geometry of FeF3
The full table of thermodynamic properties can be obtained by calculating thermal functions and selecting the enthalpy of formation. The table consists of thermal functions in a wide temperature range; equilibrium constants for a given reaction, e.g., dissociation; basic thermochemical quantities (enthalpy of formation at 0 K and room temperature, enthalpy of a given reaction); and equations approximating the reduced Gibbs energy function in the same temperature range. It should be noted that approximation is carried out using several conjugated piecewise functions. The heat capacity values at the conjugation points and their first temperature derivatives are equal for the conjugated functions.
Thermodynamic properties table for FeF3(g)
-----------------------------------P=1 atm---------------------------------
IRON TRIFLUORIDE FeF3(g)
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FeF3=Fe+3F ΔкH(0)= 1383.438 kJ/mol
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T(K) : Cp : Φ : S : H(T)-H(0) : lgK
(J/(K.mol) kJ/mol
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100 49.414 208.324 247.919 3.959 -708.7343
200 59.630 238.319 285.548 9.446 -345.9280
298.15 67.274 258.226 310.864 15.694 -226.2024
300 67.393 258.552 311.280 15.819 -224.6962
5700 83.075 465.758 546.243 458.765 6.3363
5800 83.077 467.158 547.688 467.072 6.5638
5900 83.080 468.536 549.109 475.381 6.7840
6000 83.082 469.890 550.505 483.689 6.9970
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M = 112.84220
ΔfH(0) = -739.957 kJ/mol
ΔfH(298.15) = -742.006 kJ/mol
Snucl = 20.256 J/(K.mol)
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T= 298- 1500K, X=T/10000 :
Φ = 4.688608E+02 + 6.786536E+01*ln(X) - 3.604143E-03*X + 8.173496E-01*X+ 1.590141E+02*X - 4.055775E+02*X + 5.362902E+02*X J/(K.mol)
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T= 1500- 6000K, X=T/10000 :
Φ = 5.097200E+02 + 8.307927E+01*ln(X) - 1.070131E-02*X + 1.542127E+00*X+1.627659E-01*X - 1.008190E-01*X + 3.264821E-02*X J/(K.mol)
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