Activity Coefficient Measuring and Modeling for a Single and Symmetrical Mixture in a Mixed Solvent and Friedman’s Footprint of a Higher-Order Limiting Law

Abstract

This study is conducted to investigate the HCl + NaCl + H2O + C2H5OH mixed electrolyte systems. The experimental activity coefficients are collected through measuring the electromotive force by using a cell containing pH and silver chloride electrodes in different alcohol mass fractions w(C2H5OH) in H2O (where w = 0.10, 0.20, and 0.50). All the used electrolyte molalities are between 0.01 and 2.5 mol kg–1, at 298.15 ± 0.01 K. Modeling is achieved using mean activity coefficients data for single and mixed HCl and NaCl in mixed solvent. A detailed study of Pitzer’s equations regarding effectiveness of nonionic species is taken into account. The result shows that this approach is a valuable aspect of the Pitzer equation for activity coefficient correlation of pure and mixed electrolytes, in mixed solvent media. The result underlines the importance of including Friedman’s higher-order limiting law (HOLL) regarding fitting the activity coefficient data for symmetric mixture, that is, not only theoretically accurate but also practically important. It seems that this work would be considered as the first experimental observation for the HOLL to correlate the activity coefficient of symmetrical mixture.

Quaternary System Thermodynamic Investigation in a Mixed Solvent: NaCl + KCl + N,N-Dimethylformamide + H2O

“…Accordingly, using the Nernst equation, the empirical mean activity coefficients of NaCl in the mixed-salt systems were deduced by where γ ±R,NaCl is the activity coefficient of NaCl at reference molality. To determine γ ±R,NaCl , it was not possible to perform the procedure adopted in refs , , , and , i.e., by setting the ternary ion-interaction parameters equal to zero and evaluating this quantity because the reference ionic strength of the present work is significantly higher; hence, in this study, γ ±R,NaCl was treated as a fitting parameter along with the ternary parameters, and their values are listed in Table .…”

Thermodynamic Study of Binary Sodium Chloride and Rubidium Chloride in Mixed Methanol–Water Employing the EMF Method

“…The most conventional systematic empirical methods applied to measure the thermodynamic properties are the isopiestic vapor pressure, − hygrometric method, calorimetric measurement, , and potentiometric (EMF) measurement. − While exploiting the various experimental approaches, the potentiometric method was found to be an attractive alternate and efficient technique because of its relative simplicity, continuous determination, accuracy, and rapidity. , Until now, various works have been published concerning the investigation of the thermodynamic behavior of electrolyte systems using potentiometric techniques. However, in spite of the successful achievements of electrolyte behavior investigations in aqueous media, little attention has been paid to the pure and mixed electrolyte studies in mixed solvent or in nonaqueous media and they are still too scarce. − …”

“…In the course of various methods for thermodynamic study of the analogous quaternary system, when nonelectrolyte is liquid, no more tool except for EMF made it plausible to evaluate the activity coefficients and subsequent thermodynamic quantities. − Our group has lately made use of the potentiometric method and Pitzer ion interaction and the modified Pitzer approaches to determine and describe the interactions between nonelectrolyte (amide, carbohydrate, and alcohols) and inorganic salts in multicomponent solutions, namely, the ternary and quaternary systems of mixed electrolytes (NaCl+KCl) in mixed solvents (such as N , N -dimethylformamide + water) and in aqueous alcohol solutions. ,, …”