XCVI. Intermolecular force and coefficient of self-diffusion

In this paper the Chapman-Enskog theory of non-uniform gases, as applied to the phenomenon of self-diffusion, has been utilized to evaluate the intermolecular force constants. The collision integrals occurring in the Chapman-Enskog formula for self-diffusion, as evaluated by Hirschfelder, Bird and Spotz by assuming the 12 : 6 power form of the Lennard-Jones potential function, have been used. The temperature variation of self-diffusion has been utilized to obtain the constant ε of the Lennard-Jones function, which represents the maximum negative energy of interaction of two molecules. The intermolecular separation r 0 for zero interaction energy occurring in the same potential function has been calculated by actual substitution. The recent data on self-diffusion as reported by Winn, Winter and others have been used to obtain these constants and the values compared with those given by Hirschfelder et al. from viscosity and virial coefficient data.