Equation of State for Nonpolar Fluids: Prediction from Boiling Point Constants

A new corresponding states correlation for the second virial coefficient of non- polar fluids in terms of the boiling point constants is preseInted. The scaling con- stants are the normal boiling point temperature, Tbp , which is used to form a dimensionless temperature and the liquid density at the normal boiling point, \bp , which is used to form a dimensionless second virial coefficient. The proce- dure has been examined for a large number of substances including noble gases, diatomic molecules, saturated hydrocarbons up to C8 , and a number of aliphatic, aromatic, and cyclic hydrocarbons. The resulting correlation has been applied to predict the equation of state of fluids over the range from the vapor- pressure curve to the freezing curve at various temperatures from the triple point up to the nonanalytical critical region. The equation of state has been applied to reproduce the liquid density of a great number of compounds both in the saturation and compressed states, at temperatures up to 2000 K and pressures up to 10000 bar, within an accuracy of a few percent. In particular we have shown that knowledge of two readily measurable constants is sufficient to determine the pvT surface of pure normal fluids having a variety of structural complexities.