Extension of Chen's (1982) theory to correlate densities of aqueous electrolytes

Abstract

The model proposed by Chen et al. for treating nonideality in concentrated electrolyte solutions has been extended to the correlation of the densities of solutions of single electrolytes (1: 1, 2: 1, 1:2, and 2:2) in terms of Chen's energy interaction parameters rca,,, and T , , ,~~. At any single temperature, only three adjustable parameters, v;(the partial molar volume of the solute at infinite dilution), and the pressure derivatives (dTca,ffl/dp)r and (dTffl,ca/dp), are required for correlating the density as effectively as the conventional treatment employing a power series in (molality)"2. For some electrolytes, only the latter two parameters are required, as tabulated values also lead to satisfactory correlations.The treatment can be extended to cover the temperature range 0-100°C, using either r,,,,, and T , , ,~~ values derived from activity or osmotic coefficients, or constant rca,,, and T , , ,~~ values, but the irregular variation with temperature of the pressure derivatives precludes their representation by simple analytical functions, and individual values of the pressure derivatives at each temperature are necessary.

Apparent molal volumes of the solutions of CaCl2 and Ca(NO3)2 in ethanol at 298.15: experimental data and correlation by local composition models

“…Like the previous works [5,9,10], the pressure derivative of the PDH equation have been used as the LR contribution in excess volume and the SR contribution is provided by the LC models. The SR contributions obtained from the LC models have been given in detailed in elsewhere [8,10]. The limiting partial molal volume of the electrolyte, φ 0 v , is provided by Redlich-Meyer equation.…”

“…The Pitzer model has been applied for correlation of the apparent molal volume of aqueous NaCl solutions by Rogers and Pitzer [7]. Humffray [8] has extended e-NRTL model for correlation of the densities of aqueous electrolyte solutions. The authors applied self-consistent local composition (SCLC) models [9], non-random factor (NRF) model, modified NRTL model and extended Wilson model [10] for this purpose.…”

Correlation of the osmotic coefficients of the solutions of 1:1 salts in methanol by modified local composition models at 298.15K

“…In the LC models it is assumed that the excess Gibbs energy of electrolyte solutions and consequently activity coefficients has been composed from two long-range (LR) and short-range (SR) contributions [8,[14][15][16][17]:…”

“…Z is the coordination number and was set to 8 [14]; k E and k S are the adjustable parameters of the model. 3.…”

“…Therefore, prediction of thermodynamic properties of multi-component systems is possible if only binary parameters of involved species are known [13]. Besides, because of non-linear dependency of excess Gibbs energy to the model parameters, expression for excess volume or excess enthalpy of the electrolyte solutions 0021 provided by LC models contains the excess Gibbs energy parameters [14,15]. These parameters are determined by fitting the experimental activity or osmotic coefficient data.…”