Prediction of Activity Coefficients for Uni‐univalent Electrolytes in Pure Aqueous Solution

Abstract

Parameter-free activity coefficient equations were tested in addition to those containing one, two, three or four electrolyte-dependent parameters with the experimental activity coefficients obtained from the literature data for aqueous solutions of the following electrolytes at 298.15 K: KCl, NaCl, RbCl, KBr, RbBr, CsBr, KI, RbI, KNO 3 , and KH 2 PO 4 . The experimental activity coefficients of each electrolyte considered can be reproduced within the uncertainty of the measurements up to the molality of the saturated solution by using a three-parameter equation of the extended Hückel type. The best Hückel equations are given for all electrolytes in question. The results from the present studies reveal that the parameterfree equations can be reliably used in thermodynamic studies only for very dilute electrolyte solutions. On the other hand, in most cases, a good agreement with the experimental data is obtained with the one-parameter equations of Bromley [14] and Kusik and Meissner [13], with the two-parameter equation of Bretti et al. [15], and with the three-or four-parameter equation of Hamer and Wu [19] in addition to the three-parameter Pitzer equation [23], with almost all parameter values suggested in the literature. In several cases, these equations seem to apply to much higher molalities than those used in the parameter estimations. Therefore, the best of these equations may have important applications in calculations associated with the dissolution and crystallization processes of these salts.

Re-evaluation of the thermodynamic activity quantities in aqueous alkali metal nitrate solutions at T= 298.15 K

“…These values are not considered here because they have been determined from the tabulated activity and osmotic coefficients of Hamer and Wu [24], which on the other hand are included in the present tests. In a very recent study [27] …”

Re-evaluation of the Thermodynamic Activity Quantities in Aqueous Solutions of Uni-univalent Alkali Metal Salts of Aliphatic Carboxylic Acids and Thallium Acetate at 25 °C

“…Literature Values. The values in Tables 5 to 21 were compared with the activity and osmotic coefficients presented by Robinson and Stokes, 2 Hamer and Wu, 13 and Pitzer and Mayorga. 8 The comparisons with the literature values are shown in Figure 6 for sodium formate, Figure 7 for lithium acetate, Figure 8 for sodium acetate, Figure 9 for potassium acetate, Figure 10 for rubidium acetate, Figure 11 for cesium acetate, Figure 12 for thallium acetate, Figure 13 for sodium propionate, Figure 14 for sodium butyrate and sodium valerate, Figure 15 for sodium hydrogen malonate, Figure 16 for potassium hydrogen malonate, For the recommended activity values, the values obtained from eqs 5 and 6 were used when available, and the values from eqs 1 and 2 were used in the other cases.…”

Traceable Mean Activity Coefficients and Osmotic Coefficients in Aqueous Calcium Chloride Solutions at 25 °C up to a Molality of 3.0 mol·kg–1

“…The new parameter values for CaCl 2 were tested with the data used in the estimation and with the most dilute isotonic points in the set of Stokes 3 measured against NaCl solutions (ref 6 also gives the Huckel parameters for NaCl solutions) and in that of Spedding et al 7 The latter data were measured against KCl solutions; however, the isopiestic molalities for KCl and CaCl 2 solutions are not readily available in that paper, but they have been hidden in their wide tables of isopiestic data of rare earth chlorides. They are reported, however, in detail in Table I of the review of Rard et al 8 where all existing isopiestic data available for CaCl 2 solutions up to the publication date against KCl, 5,7 NaCl, 3,9 and H 2 SO 4 3,10 solutions have been collected. The resulting parameter values for CaCl 2 solutions were also tested with the galvanic cell data measured by Lucasse, 11 Shedlovsky and MacInnes, 12 and McLeod and Gordon 13 on concentration cells with transference; by Lucasse, 11 Fosbinder, 14 Scatchard and Tefft, 15 and Mussini and Pagella 16 on cells with calcium amalgam electrodes; by Shatkay 17 and Briggs and Lilley 18 on cells with calcium ion sensitive membrane electrodes; and by Sahay 19 on cells with lead−lead oxalate electrodes.…”

“…The Huckel equation used (see below and ref 4) to describe the thermodynamic properties of dilute solutions has two electrolyte-dependent parameters B and b 1 : the former is linearly related to the ion-size parameter a* in the Debye− Huckel theory, and the latter is the coefficient of the linear correction term with respect to the molality. B and b 1 for dilute CaCl 2 solutions were now obtained from the isopiestic data of Robinson 5 for KCl and CaCl 2 solutions, and the points where the CaCl 2 ionic strength is smaller than 1.6443 mol·kg −1 were included in the estimation.…”