Isopiestic determination of the activity coefficients of some aqueous rare-earth electrolyte solutions at 25 0C. 6. Eu(NO3)3, Y(NO3)3, and YCl3

The osmotic coefficients of aqueous Eu(NO3)3, Y(NO3)3, and YCl3 have been measured at 25 0C from dilute solution to supersaturated concentrations with the isoplestic method. Least-squares equations were fitted to these osmotic coefficients, which were then used to calculate water activities and mean molal activity coefficients. Pitzer's equations were also fitted to the lower-concentration data. These results are compared to published activity data for rare-earth chlorides, perchlorates, and nitrates. A total of 40 rare-earth salts have now been studied, and their activities are discussed in terms of cation hydration and anion-cation interactions. Density data are also reported for Y(NO3)3 solutions