Extended equation for the coexistence curve of molecular liquids in the vicinity of a critical point

An extended equation of state for substances along a phase interface, based on the Van der Waals model of a gas with fluctuations of the order parameter is confirmed by experimental data along the coexistence curve of a wide class of homogeneous and inhomogeneous molecular liquids under the Earth’s field of gravity. It is shown that the parameters of the extended equation for the coexistence curve of homogeneous and spatially inhomogeneous molecular liquids are linear functions of the compressibility factor. This allows us to predict the parameters of the equations of state of molecular liquids that are difficult to investigate experimentally.