The volumetric and thermochemical properties of YCl 3(aq), YbCl 3(aq), DyCl 3(aq), SmCl 3(aq), and GdCl 3(aq) at T=(288.15, 298.15, 313.15, and 328.15) K and p=0.1 MPa

Abstract

Relative densities and massic heat capacities have been measured for acidified aqueous solutions of YCl 3(aq), YbCl 3(aq), DyCl 3(aq), SmCl 3(aq), and GdCl 3(aq) at T=(288.15, 298.15, 313.15, and 328.15) K and p=0.1 MPa. These measurements have been used to calculate experimental apparent molar volumes and heat capacities which, when used in conjunction with Young’s rule, were used to calculate the apparent molar properties of the aqueous chloride salt solutions. The latter calculations required the use of volumetric and thermochemical data for aqueous solutions of hydrochloric acid that have been previously reported in the literature. The concentration dependences of the apparent molar properties have been modeled using Pitzer ion interaction equations to yield apparent molar volumes and heat capacities at infinite dilution. The temperature and concentration dependences of the apparent molar volumes and heat capacities of each trivalent salt system were modeled using modified Pitzer ion interaction equations. These equations utilized the revised Helgeson, Kirkham, and Flowers equations of state to model the temperature dependences of apparent molar volumes and heat capacities at infinite dilution. Calculated apparent molar volumes and heat capacities at infinite dilution have been used to calculate single ion properties for the investigated trivalent metal cations. These values have been compared to those previously reported in the literature. The differences between single ion values calculated in this study and those values calculated from thermodynamic data for aqueous perchlorate salts are also discussed.