Vapor Pressures of Aqueous Melts at 130° Containing LiNO3-KNO3

Transpiration vapor pressure measurements were made on LiNO 3 -KNO 3 -H 2 O aqueous melts at 129.51°C. The water mole ratio, R H , was varied from approximately 0.2 to 1.0 mol H 2 O/mol NO 3 . The salt mole fraction, R L , was varied from 0.4493 to 0.7000 mol Li+/mol NO 3 . The vapor pressures show within experimental error a linear dependence on R H at all values of R L . This behavior is consistent with earlier results on LiNO 3 -KNO 3 melts containing water and heavy water with R L = 0.500 mol Li+/mol . The vapor pressures are also a function of R L and computation of the water concentration dependence of the activity coefficients of LiNO 3 and KNO 3 indicates preferential interaction of water with lithium ion over potassium ion. The results are discussed in light of models which have been proposed for aqueous melts.