Activity Coefficients of NaCl in Fructose + Water at 298.15 K

Abstract

The mean ionic activity coefficients of NaCl in fructose + water mixtures were experimentally determined at 298.15 K from electromotive force measurements of the following electrochemical cell containing two ion-selective electrodes (ISE): Na−ISE|NaCl(m),fructose(w),H2O(1−w)|Cl−ISE. The molality (m) varied between (0.005 and 3.5) mol kg-1, while the mass fraction of fructose in the mixture (w) was 0, 0.1, 0.2, 0.3, and 0.4. The emf values were analyzed using different models which employed extended Debye−Hückel equations and those of Pitzer, Scatchard, and Sen for describing the variations in activity coefficients with concentration. Results obtained with the different models were in good agreement. The interaction parameters of each model were comparatively analyzed with those of other similar systems reported in the literature, and discussion is presented concerning their variation with properties of the medium, particularly the dielectric constant. The free energy of transfer of the NaCl from the water to the mixed solvent was determined and its variation with the composition of the solvent is discussed in terms of ion−ion and ion−solvent interactions. Also determined was the primary hydration number of the NaCl, which was compared with results from the literature. Finally, the parameters of interaction g ij and salting constant k s were estimated.

Activity coefficients of NaF in (glucose+water) and (sucrose+water) mixtures at 298.15 K

“…E * is the apparent standard potential (molal scale) of the cell and contains the potential of asymmetry of both selective electrodes [14][15][16]. In this study, these asymmetry potentials were always small and independent of the solvent composition.…”

“…In two previous studies [13,14], we have undertaken the study of some thermodynamic processes in (NaCl + sugar + water) systems. The present closely related study includes the determination of mean ionic activity coefficients in aqueous NaF solutions containing both glucose and sucrose in an attempt to provide fundamental knowledge on ionic interactions in (electrolyte + sugar + water) solutions in relation to the structure and properties of the medium.…”

“…The temperature was kept constant at 298.15 for all the studies. These studies were carried out using potentiometric techniques which have advanced markedly in recent decades due mainly to the development and improvement of new ion-selective electrodes (ISEs) [13][14][15][16][17][18][19][20][21]. Now, these electrodes are not only valuable for analytical use, but also may be employed in determining thermodynamic and transport magnitudes.…”

Empirical and theoretical models of equilibrium and non-equilibrium transition temperatures of supplemented phase diagrams in aqueous systems (IUPAC Technical Report)

“…Morel and co-workers [42][43][44][45][46][47][48][49], Wang and co-workers [50][51][52][53][54][55][56][57][58][59][60][61], and Hernandez-Luis et al [62,63] used the transfer functions approach and reported a very comprehensive set of data for the interaction parameters of sugars with several electrolytes.…”

“…Actually, a few works deal with Pitzer equations in aqueous sugar + electrolytes mixtures, and all of them treat the system as a pseudobinary system, that is, the mixture water + sugar is considered as a pure solvent with the dielectric and viscosity properties of the mixture. Thus, the experimental activity coefficients of NaCl in glucose, sucrose, and fructose aqueous solutions [52,63] and CaCl 2 in maltose and lactose aqueous solutions [61] at 25 °C were described using Pitzer pseudo-binary coefficients with an accuracy similar to the transfer functions approach given by eqs. 34-35.…”