A SIMPLE FUCTIONAL REPRESENTATION, EXTRAPOLATION, AND INTERNAL CONSISTENCY OF SECOND VIRIAL COEFFICIENTS

摘要

The virial equation of state when truncated after the second coefficient provides reliable values for the compression factor, Z, up to about one-half the critical density. Unfortunately, pure and cross second virial coefficients are not always available. To overcome this problem, these coefficients must be available experimentally or predicted using a correlation. Naturally, the latter procedure is preferable. Numerous correlations for pure and cross second virial coefficients have appeared in the literature; one of most widely used being that of Tsonopolous . This corresponding states correlation uses the acentric factor and the critical pressure and temperature as characteristic parameters for simple molecules. More complex compounds, such as polar molecules, require reduced dipole moment and constants for specific groups of molecules as well as different temperature functions.