New Universal Relations for Liquid-Vapor Phase Equilibrium

Universal relations between the saturation pressure pLV and the value of ϕ=ΔhLV/ΔνLV−pLV, where ΔhLV .is the latent heat of evaporation and ΔνLV is the volume change of the vapor-liquid transition, and the product of the orthobaric densities ρL and ρV of the liquid and vapor at coexistence have been discovered. In the temperature range from the triple point to T/Tc≈0.9, these relations obey a power law with universal exponents. At temperatures 0.9<T/Tc≤1, pLV and ϕ depend linearly on ln(ρLρV) with retention of universality for substances of different nature.