Ideal Gas Thermodynamic Properties of Ethane and Propane

The thermodynamic properties ${\mathrm{(C}}_p^{\mathrm{o}}{\mathrm{,\hspace{0.17em}S}}^{\mathrm{o}}{\mathrm{,\hspace{0.17em}H}}^{\mathrm{o}}{\mathrm{-H}}_0^{\mathrm{o}}{\mathrm{,\hspace{0.17em}(H}}^{\mathrm{o}}{\mathrm{-H}}_0^{\mathrm{o}}{\mathrm{)/T,-(G}}^{\mathrm{o}}{\mathrm{-H}}_0^{\mathrm{o}}{\mathrm{)/T,\hspace{0.17em}\Delta Hf}}^{\mathrm{o}}{\mathrm{,\hspace{0.17em}\Delta Gf}}^{\mathrm{o}}\hspace{0.17em}\mathrm{and\; log}\mathrm{\hspace{0.17em}Kf)}$ for ethane and propane in the ideal gaseous state in the temperature range from 0 to 1500 K and at 1 atm were calculated by statistical thermodynamic methods based on a rigid‐rotor harmonic‐oscillator model. The internal rotation contributions to thermodynamic functions were evaluated by using a partition function formed by summation of internal rotation energy levels. The calculated heat capacities and entropies compare favorably with available experimental data.