#### 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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