Liquid–Vapor Phase Transitions and Critical Properties of the C3H7OH–C6H14 System

Abstract

Proceeding from the experimental (p,T,x) and (p,ρ,T,x) dependences for mixtures of 1-propanol and n-hexane (mole fractions 0.2, 0.5, 0.8, and 0.9) in the two-phase (liquid–vapor), single-phase (liquid and vapor), near-critical, and supercritical regions, the parameters of the points of liquid–vapor phase transformations have been determined by the method of isochore kinks p = f(T)ρ,x and the parameters of the critical points have been found by the semigraphical method with allowance for the scaling behavior. The dependences of the pressure on temperature, density, and composition along the phase-coexistence curve are described by a three-parameter polynomial equation of state: expansion of the compressibility factor Z = p/RTρ in powers of the reduced density, reduced temperature, and composition. The mean relative error of deviation of the calculated pressures from experimental values does not exceed 1%. The temperature dependence of the system density along the liquid–vapor phase-coexistence curve is described by two power-law functions at critical exponent β0 = 0.338 ± 0.002: far from the critical point and in the symmetric part of the equilibrium curve. The mean relative error is 1.47%.