Temperature Dependence of Vapor Pressures over Saturated Aqueous Solutions at Invariant Points of the NaCl + KNO3 + H2O, NaCl + Na2CO3 + H2O, and NaCl + Na2SO4 + H2O Systems

Abstract

Vapor pressures of water over saturated solutions with regard to two salts, in the NaCl + KNO3 + H2O, NaCl + Na2CO3 + H2O, and NaCl + Na2SO4 + H2O systems are reported in the (278 to 323) K temperature range. The determined vapor pressures were used to obtain the water activities, the molar enthalpies of vaporization and the osmotic coefficients. Compositions of invariant points from the literature were correlated as a function of temperature with the aid of quadratic equations. These equations served to determine the molar enthalpies of solution.