Calculation of thermodynamical properties in liquid-gas region

The paper presents the mathematical model used for the computation of thermodynamic functions of state in the liquid and gas domain, with the aid of statistical thermodynamics of Lennard-Jones fluid. To calculate the thermodynamic properties of a real fluid, we used the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin equation of state, the Chunxi-Yigui-Jiufang equation of state based on the simple perturbation theory, and the complex Tang-Tong-Lu model based on the solution of the Ornstein-Zernike equation obtained by means of the perturbation theory. The analytical results are compared with the thermodynamical data, and with the results obtained from classical thermodynamics. \\@ng\