Calculation of the speed of sound and other thermophysical properties

A mathematical model is featured for computing the velocity of sound and ot her thermophysical properties in the liquid, the gas, and the two-phase dom ains with the help of statistical thermodynamics. All important contributio ns (translation, rotation, internal rotation, vibration, intermolecular pot ential energy, and influences of electron and nuclei excitation) are includ ed. To calculate the thermodynamic properties of real gases, we develop the cluster theory, which yields better results than the virial equation. For the realm of real liquids, the Johnson-Zollweg-Gubbins model (Johnson, J, K ,, Zollweg, J, A., and Gubbins, K. E,, "The Lennard-Jones Equation of State Revisited," Molecular Physics, Vol. 78, No, 3, 1993, pp. 591-618) based on the modified Benedict-Webb-Rubin equation was applied. The Lennard-Jones i ntermolecular potential was used. The analytical results are compared with the experimental data and models obtained by classical thermodynamics and s how relatively good agreement.