P-V-T-X MEASUREMENTS OF AQUEOUS MIXTURES AT SUPERCRITICAL CONDITIONS

We report P-V-T-x measurements for five binary systems: water + methane, water + n-hexane, water + n-octane, water + benzene, and water + nitrogen at supercritical conditions for several compositions. The experimental data were obtained along isotherms with a phase-equilibrium cell designed for accurate measurements at pressures up to 100 MPa. The uncertainties in temperature, pressure, density, and concentration are +/- 0.01 K, +/- 0.2 %, +/- 0.2 %, and +/- 0.002 mole fractions, respectively. The behavior of the second virial coefficient, the excess volume, and the excess Gibbs free energy is also discussed.