High-pressure densities and derived volumetric properties (excess and partial molar volumes, vapor-pressures) of binary methanol + ethanol mixtures

The densities of five (0.08564, 0.19998, 0.41971, 0.68017, and 0.84236 mol fraction of methanol) binary methanol + ethanol mixtures have been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from T = (298.15 to 423.15) K and at pressures up to 40 MPa. The total uncertainty of density, temperature, pressure, and concentration measurements were estimated to be less than 0.15 kg m−3, 15 mK, 5 kPa, and 10−4, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The effect of temperature, pressure, and concentration on the density and derived volumetric properties such as excess and partial molar volumes was studied. Using the analytical extrapolating technique the vapor-pressure and saturation liquid densities of the mixture were derived. The measured densities were used to develop polynomial type equation of state for the mixture. The structural properties such as direct and total correlation function integrals and clusters size (excess coordination number) were calculated using the Krichevskii function concept and equation of state for the mixture at infinite dilution.