Lennard-Jones and Devonshire Equation of State of Compressed Gases and Liquids

The reduced equation of state for compressed gases and liquids is computed according to the theory of Lennard-Jones and Devonshire for a large number of temperatures and densities. The corrections due to gas imperfection of internal energy, specific heat, and entropy as well as the compressibility factor (pv/RT) are expressed in terms of reduced variables. The calculations were made by punched-card methods. A comparison is made between experiment and theory. It is shown that the theory of Lennard-Jones and Devonshire is unsatisfactory at densities near the critical point and lower but improves at higher densities becoming better for normal liquids. Such results were to be expected from the nature of the cell or free-volume method.