Intermolecular Potentials. I. Carbon Tetrafluoride and Sulfur Hexafluoride. II. Carbon Dioxide

Abstract

Experimental second virial coefficient data for carbon tetrafluoride, sulfur hexafluoride, and carbon dioxide have been used to investigate the intermolecular potentials of these molecules on the basis of a Lennard‐Jones model. Force constants for the fluoride molecules can be fitted rather satisfactorily, but the constants so derived do not agree with those derived from other gaseous properties, e.g., the critical data. This result may be due to the assumption of central forces for the symmetrical fluoride molecules. For carbon dioxide it was found that the derived force constants varied with temperature, the high temperature data yielding lower values of the collision diameter r₀. The results can be interpreted on the basis of a partial association. A likely configuration for the resulting dimer is suggested.