Experimental study of the isomorphism behavior of weakly (CVX) and strongly (CPX, KTX) singular properties of 0.082 n-hexane + 0.918 water mixtures near the upper critical point

One-phase PVTx properties, three-phase (L-L-V) and two-phase (L-V) boundary properties (PS, TS, ρS), the critical parameters (PC, TC, ρC) of dilute (0.082 mole fraction of n-hexane) n-hexane + water mixture at temperatures from 309 to 677 K and pressures from 0.012 to 61 MPa, including upper critical point and supercritical conditions have been measured with a constant-volume piezometer technique. The expanded uncertainty of the density, pressure, and temperature measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.10% (at high densities) to 0.12% (at low densities), 0.0005 to 0.005 MPa, and 15 mK, respectively. The crossover from pure-like to mixture like critical behavior of the weakly (CVX) and strongly (CPX, KTX) singular properties in terms of the principle of isomorphism of critical phenomena in binary mixtures has been studied.