Near critical measurements of HmEandVmE for { xCO2 + (1 − x)SF6} and measurements made over the pressure range 2.5 to 10.0 MPa at the temperature T = 301.95 K

Abstract

A flow mixing calorimeter, followed by a vibrating tube densimeter, has been used to measure excess molar enthalpies HmEand excess molar volumesVmE of {xCO2+ (1 −x)SF6}. Measurements over a range of mole fraction x have been made at the temperatures T= 302.15 K and T= 305.65 K at the pressures (3.76, 5.20, 6.20, and 7.38) MPa. The lowest pressure 3.76 MPa is close to thecritical pressure of SF6 and the highest pressure 7.38 MPa is close to the critical pressure of CO 2. Measurements atx= 0.5 have been made over the pressure range (2.5 to 10.0) MPa at the temperature 301.95 K. Some of the measurements are very close to the critical locus of the mixture. The measurements are compared with the Patel–Teja equation of state which reproduces the main features of the excess function curves as well as it does for similar measurements on {xCO2+ (1 −x)C2H6} and{xCO2+ (1 −x)C2H4} . The equation was used to calculate residual enthalpies and residual volumes for the pure components and for the mixture, and inspection of the way these combine to give excess enthalpies and volumes assisted the interpretation of the pressure scan measurements.