AQUEOUS MIXTURES TO SUPERCRITICAL TEMPERATURES AND AT HIGH-PRESSURES

Thermophysical properties of dense supercritical water with special emphasis on dielectric permittivity are discussed. Phase diagrams and some critical curves of the binary systems H//2O-H//2, H//2O-N//2, H//2O-O//2, H//2O-CH//4 and H//2O-He to 450 degree C and 200 MPa are shown. H//2O-He has a type I critical curve. A rational equation of state to calculate phase diagrams and critical curves for polar-nonpolar systems is described. Measurements with the ternary systems H//2O-CH//4-NaCl are presented. 2 mol% of added NaCl shifts the phase separation H//2O-CH//4 by 100 degrees to higher temperatures. The excess Gibbs energy for homogeneous supercritical H//2O-N//2-mixtures to 200 MPa is shown. The static permittivity of supercritical H//2O-benzene mixtures is presented as an example of dielectric behavior of polar-nonpolar mixtures in general.