Determination of binary data for neptunium(V) nitrate

Abstract

Summary A stock solution consisting of a highly concentrated binary solution of neptunium(V) nitrate [NpVO2(NO3)] in water (about 4.5mol kg-1) was prepared and used to obtain a series of binary NpVO2(NO3)-H2O or ternary NpVO2(NO3)-HNO3-H2O solutions whose neptunium concentration ranged between about 0.22 and 4.5mol kg-1. Water activity and/or osmolality of these binary and ternary solutions were measured and used to calculate the variation of the osmotic coefficient of the real or fictive binary solutions versus NpVO2(NO3) concentration. The variation of the mean stoichiometric activity coefficient of this salt in water was then calculated. The densities of these solutions were also measured and used to express the activity coefficient values on both the molar and molal concentration scales.