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The mean activity coefficients for CsCl in N-methylformamide or urea ( w) + HO (1 − w) systems were determined in this work by potentiometry, using ion-selective electrodes at 298.15 K. The value of mass fraction w was varied between 0.00 and 0.40 in five unit-steps and the molality of CsCl was between 0.0020 and 1.4009 mol·kg. The experimental data have been correlated with the Pitzer, modified Pitzer and the extended Debye-Hückel equations. The resulting values of the mean activity coefficients, the osmotic coefficients and the standard Gibbs energy of transfer, together with the Pitzer ion-interaction parameters ( β, β and C), extended Debye-Hückel parameters ( a, c and d), and modified Pitzer parameters ( b, B, C) are reported for the investigated systems. [ABSTRACT FROM AUTHOR]

Abstract: Electromotive force (emf) of the chemical cell without liquid-junction K-ISE | RbCl/CsCl ( m E) | ISE-Cl and K-ISE | RbCl/CsCl (m E), amide (m N) | ISE-Cl, have been measured at 298.15 K, where m E =(0.005 to 0.5) mol kg−1 and m N= (0.05 to 3.0) mol kg−1. The activity coefficients of RbCl/CsCl in amide (acetamide, propanamide, and n-butanamide)+water mixture can be obtained from these electromotive force data and in the mean time the Gibbs free energy interaction parameters of RbCl/CsCl+amide pair in water, g EN, as well as the salt constant, k S, can be evaluated. The results show that both g EN >0, k S >0 at 298.15 K, and all the activity coefficients of electrolyte in amide+water mixture increase with increasing the m N, but it is a little complicated for the dependence of activity coefficients on m E. These thermodynamic parameters were discussed in terms of a model of the structural interaction and electrostatic interaction and the dependence of them on the number of carbon atoms in amide as well as the radius of metal ions were interpreted by the group additivity principle. [Copyright &y& Elsevier]

In this paper, the potentiometric method was carried out to investigate the thermodynamic properties of the RbF + Rb 2 SO 4 + H 2 O and CsF + Cs 2 SO 4 + H 2 O ternary systems over total ionic strengths from (0.01–0.70) mol·kg −1 for different ionic strength fractions y B of Rb 2 SO 4 /Cs 2 SO 4 with y B = 0.00, 0.30, 0.60 and 0.90, at 298.2 K. The Harned model and the Pitzer model were used to correlate the experimental data. The Harned coefficients and the Pitzer mixing parameters were evaluated by multiple linear regression technique. Moreover, the mean ionic activity coefficients of RbF/CsF and Rb 2 SO 4 /Cs 2 SO 4 , the osmotic coefficients, and the excess Gibbs energies of the studied systems were calculated, respectively. [ABSTRACT FROM AUTHOR]

Thermodynamic properties of (RbF + RbCl + H 2 O) and (CsF + CsCl + H 2 O) systems were determined by the potentiometric method for different ionic strength fractions y B of RbCl/CsCl at 298.2 K. The Pitzer model and the Harned rule were used to fit the experimental values. The Pitzer mixing parameters and the Harned coefficients were evaluated. In addition, the mean ionic activity coefficients of RbF/CsF and RbCl/CsCl, the osmotic coefficients, and the excess Gibbs energies of the systems studied were calculated. [ABSTRACT FROM AUTHOR]

This paper reports the thermodynamic properties of CsF in (Urea + H 2 O) or ( N -methylformamide + H 2 O) mixed solvents by potentiometric method at 298.2 K. The experimental data are fitted using the Pitzer, modified Pitzer and extended Debye-Hückel equation. The mean activity coefficients, osmotic coefficient and excess Gibbs free energies are obtained and the corresponding derived parameters are reported at the same time. The standard free energy of transference and the primary hydration number are also obtained. [ABSTRACT FROM AUTHOR]

The (solid + liquid) equilibrium (SLE) and (liquid + liquid) equilibrium (LLE) of RbCl/CsCl + ethylene carbonate (EC) + H 2 O ternary systems were carefully investigated at 298.15 K. The SLE and LLE data were correlated by the corresponding equations respectively. Furthermore, the thermodynamic properties of RbCl/CsCl in the EC–water systems were determined by potentiometric method at T = 298.15 K. The experiment data were correlated by the Pitzer, modified Pitzer and the extended Debye–Hückel equations. The mean activity coefficients, osmotic coefficients and excess Gibbs free energies, standard Gibbs free energy of transfer and the standard solubility product of systems were calculated. The mean activity coefficient γ ± decreases with the increase of the molality of electrolyte at the fixed mass fraction of EC. But γ ± vary abnormally with the increase of the EC content. The result of Δ G t 0 reflects the spontaneously transfer of the electrolytes from water to the mixed solvents. [ABSTRACT FROM AUTHOR]

This article deals with the mean activity coefficients of LiCl in amide–water mixtures with both ɛ -increasing co-solvent (urea–water, N -methylformamide–water), and ɛ -decreasing co-solvent ( N , N -dimethylformamide–water, N , N -dimethylacetamide–water) systems at 298.15 K by potentiometric method. Meanwhile, thermodynamic properties including the osmotic coefficients, the excess Gibbs free energy, the standard solubility product, the primary LiCl hydration number and the standard free energy of transference from water to the mixtures were also calculated. The nonideal behavior of these systems has been discussed in terms of the Pitzer, the Modified Pitzer and the extended Debye–Hückel equations parameters. [ABSTRACT FROM AUTHOR]

Activity coefficients of RbCl orCsCl in methanol + ethanol + water were determined at 298.15 K by the cells containing ion-selective electrodes (ISEs). The molalities of RbCl and CsCl are up to approximately 1 mol·kg–1in the mixed solvents, and the mass fractions offive aqueous MeOH/EtOH mixtures studied were (5/5, 10/5, 5/10, 10/10,and 15/15) %. The experimental data were optimized using the extendedDebye–Hückel, the Pitzer, and the modified Pitzer equations.The results of the apparent standard electromotive force E0* of the three equations are in good agreement. The meanactivity coefficients and the standard Gibbs energy of transfer ofRbCl or CsCl from pure water to mixed solvents (MeOH + EtOH + water)were also calculated. [ABSTRACT FROM AUTHOR]

Abstract: In this work, thermodynamic properties measurement for KCl/RbCl/CsCl in N,N-dimethylacetamide (DMA) (w)+H2O (1− w) systems (where the w =0.10, 0.20, 0.30) was carried out by potentiometric method using ion-selective electrodes at 298.15K. Modeling of the activity coefficients of these ternary systems was based on the Pitzer, the modified Pitzer and the extended Debye–Hückel equations. Meanwhile, the osmotic coefficients, the standard free energy of transference from the water to the mixture have also been reported. [Copyright &y& Elsevier]

Abstract: The thermodynamic properties of CsF in the ROH (R=methyl or ethyl)+water mixtures were determined using potentiometric measurements at 298.15K with the mass fraction of ROH varying from 0.00 to 0.30. The Pitzer, extended Debye–Hückel and Pitzer–Simonson–Clegg equations were successfully utilized to fit the experimental data based on the molality and mole-fraction-composition scale. Except for the standard cell potentials and Pitzer parameters, the mean activity coefficients, osmotic coefficients and standard Gibbs energies of transference of CsF from water to the methanol+water or ethanol+water mixtures have also been discussed herein. [Copyright &y& Elsevier]

In this paper, the mean activity coefficients for CsBr,as wellas the osmotic coefficients, the excess Gibbs free energies, the Gibbsenergies of transference, and the primary hydration in different MeOH–waterand EtOH–water mixtures at 298.15 K are calculated by potentiometricmeasurements. The cell used in this work contains two ion selectiveelectrodes (ISEs): Cs-ISE|CsBr(m), ROH(w), H2O(1 – w)|Br-ISE (R = Me andEt), and the mass fraction of ROH in the mixture (w) was varied between 0 and 0.3 in 0.1 unit steps. The experimentaldata were correlated very well by the thermodynamics equations ofPitzer, modified Pitzer, and Debye–Hückel models. [ABSTRACT FROM AUTHOR]

Activity coefficients for RbCl in different ethylene glycol water and glycerol water mixed solvents were determined at 298.15 K using potentiometric measurements. The Pitzer and extended Debye−Hückel equations were applied to describe the nonideal behavior of the electrolyte, and the corresponding coefficients were determined for each mixed solvent system. [ABSTRACT FROM AUTHOR]

For this article, a number of thermodynamic properties for MCl (M = Na, K, Rb, Cs) in tetramethylurea (TMU)-water ternary systems were investigated through potentiometric method at the temperature of 298.2 K. To fit experiment data, the Pitzer equation and the extended Debye-Hückel equation were used. The mean activity coefficients, together with excess Gibbs free energy, osmotic coefficients and standard solubility product of ternary systems are calculated. The variation of these properties in this ε r -decreasing co-solvent (TMU-H 2 O) is discussed from the aspect of ion radius, relative permittivity, ion-ion interactions and ion-solvent in the solution. Unlabelled Image • MCl + TMU + H 2 O systems (M = Na, K, Rb, Cs; TMU = tetramethylurea) • Thermodynamic properties of MCl + TMU + H 2 O by potentiometric method • The Pitzer and extended Debye-Hückel equations were used for correlation. • Electrostatic interaction and solvation influence the properties. [ABSTRACT FROM AUTHOR]