Pressure-composition relations for coexisting gases and liquids and the critical points in the system NaCl-H₂O at 450, 475, and 500°C

Pressure-temperature-composition (P, T, x) relations for the co-existing vapor and liquid phases in the system NaCl-H₂O were determined experimentally at 450, 475, and 500°C. Data for each isotherm includeP-x relations near the critical point and extend to the three-phase assemblage vapor-liquid-halite on the vapor side. On the liquid side the P-x data range from the critical point to the room-temperature halite saturation point (~25 wt.% NaCl). Critical pressures were calculated from measured pressures and compositions and classical theory. The results generally support the few data points of Urusova (1974, 1975) and Ölander and Liander (1950) but differ markedly from the extensive data of Sourirajan andKennedy (1962).