Acoustic and Volumetric Virial Coefficients of Nitrogen

Speeds of sound in nitrogen were measured at temperatures between 170 and 400 K at amount-of-substance densities between 40 and 400 mol } m&3. From these measurements, second and third acoustic virial coefficients were obtained. The parameters of two- and three-body isotropic iIntermolecular potential- energy models were optimized in a simultaneous fit to the second and third acoustic virial coefficients and the ordinary second and third virial coefficients of nitrogen reported by Nowak et al. The results, which shows that the acoustic and ordinary virial coefficients are mutually consistent, may be used to predict second and third virial coefficients, and their acoustic couInterparts, over a wide range of temperatures. The parameters of an anisotropic site-site potential- energy model were also obtained from a fit to the acoustic and ordinary second virial coefficients alone.