Thermodynamic Properties of the NaCl+H2O System. II. Thermodynamic Properties of NaCl(aq), NaCl⋅2H2(cr), and Phase Equilibria

Abstract

Equations that described the thermodynamic properties of the NaCI + H20 system were obtained from a fit to experimental results for this system. The experimental results included in the fit spanned the range of temperature of approximately 250 to 600 K and, where available, the range of pressure from the vapor pressure of the solution to 100 MPa. New equations and/or values for the following properties are given in the present work: 1) A~~ and An:.. for formation from the elements. for NaCI(cr) for 298.15 K and 0.1 MPa, 2) A~:' and An:. from the elements, as well as S:' and C;'m, all for 298.15 K, 0.1 MPa, for NaCI'2H20(cr), 3) the change in chemical potential for both NaCI and HzO in NaCI(aq) as a function of temperature, pressure, and molality, valld from 250 to 600 K and, where available, from the vapor pressure of the solution to 100 MPa. Comparison of the accuracies of experimental methods, where possible, has also been performed.

Isopiestic Determination of the Osmotic and Activity Coefficients of Li2SO4(aq) at T=298.15 and 323.15 K, and Representation with an Extended Ion-Interaction (Pitzer) Model

“…There are several previous studies that reported isopiestic data for Li 2 [10][11][12]14,15] were recalculated for consistency using current critical evaluations of the thermodynamic properties of the reference standards NaCl(aq) [7], KCl(aq) [18], and H 2 SO 4 (aq) [19]. [10,14,15], including the present results from Table 2 (excluding a few measurements as described above), are generally in good agreement.…”

Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2+(1−y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4⋅MgSO4(aq) at 298.15 K

“…or NaCl(aq) are denoted with a subscript R. The osmotic coefficient of each KCl(aq) and NaCl(aq) reference solution at 298.15 K was calculated using the ion-interaction (Pitzer) model and parameters reported by Archer [8,34].…”

“…The parameters at 298.15 K given in their errata are listed in our Table 3, and were used to calculate values of φ at the 6 experimental concentrations reported in Table 1. were recalculated for consistency using up-to-date ion-interaction models for these reference standards [8][9][10]34], where the CaCl 2 (aq) model of Pitzer et al [10] is based on refitting of results from the critical assessment of Rard and Clegg [41]. Rard and Miller [30,39] generally used two or three isopiestic standards in their isopiestic measurements and the average value of the osmotic coefficient for MgCl 2 (aq) was accepted for each equilibration.…”

“…Parameter Evaluation for MgCl 2 (aq) at 298.15 K Archer's [8] extended form of Pitzer's ion-interaction model [1] was chosen to represent the osmotic and activity coefficients of MgCl 2 (aq) at 298.15 K because it is generally able to represent these properties more accurately than the original 3-parameter model for higher valence and more soluble electrolytes. Including the…”

“…To improve the accuracy of Pitzer's ion-interaction model for representing thermodynamic properties of more soluble electrolytes, Archer [8] replaced the constant …”