The quasi-spinodal and the supercritical point in the liquid-vapor phase diagram

The generalized van der Waals equation is used to obtain equations describing the quasi-spinodal and the supercritical point parameters of a one-component substance. The special features of the quasi-spinodal in the supercritical region and in the region of the existence of an unstable phase are analyzed. Supercritical point parameters and the parameters of quasi-spinodal characteristic points are calculated for several substances.