Volumetric, rheological, and optical properties of Na-alkylsulfonates aqueous solutions at 29°C

Present paper reports density, relative viscosity and refractive index of sodium salt of 1-heptanesulfonic acid and 1-octanesulfonic acid at 29°C. Density data has been fitted to Masson empirical relation and limiting apparent molar volumes were evaluated. Viscosity A and B coefficients characterizing ion-ion and ion-solvent interactions have been evaluated by fitting viscosity data in Jone-Doles equation. Experimental and calculated properties support the strong ion-solvent interactions in solution.     

Electrohydrodynamic ionization mass spectrometry of sulfonates

Electrohydrodynamic ionization mass spectrometry has been applied to the analysis of 2-naphthol-3,6-disulfonic acid, disodium salt and 4,5-dihydroxy-2,7-naphthalenedisulfonic acid, disodium salt. The negative ion mass spectra indicate ions characteristic of the sample and no fragment ions are observed. Degrees of dissociation of the sulfonates and the ion-solvent interactions are reflected in the negative ion spectra.     

An alternative interpretation of the chemical shift of the water proton in aqueous tetraalkylammonium halide solutions at various temperatures

An alternative explanation of the behavior of proton magnetic resonance chemical shifts of the water proton in aqueous tetraalkylammonium salt solutions is presented. It involves independent ion-solvent interactions and rapid exchange on the NMR time scale with the bulk water. Our explanation fits the known data and clearly shows why the observed chemical shift is linear with molality at low concentrations.     

The eutectic system for (NH4NO3 + LiNO3 + NH4Cl) - dimethylsulfoxide from infinite dilution to fused salt

Solubility, density, refractive index and viscosity of the title system in water and dimethylsulfoxide have been measured in the composition range from the pure solvent to the pure liquid salt. Molar volumes, apparent molar volumes and other volumetric quantities have been calculated and their concentration dependences are discussed. The molar refractivities of the solvent and salt were estimated and used for a discussion of ion-ion and ion-solvent interactions. The viscosity vs. concentration plot exhibits a maximum at the salt mole fraction x₃=0.8 which cannot be described by any currently known equation.     

Specific interactions and single-lon activity coefficients in mixed electrolyte solutions

A reexamination of Guggenheim's theory of specific interactions for dilute aqueous electrolyte solutions shows that the parameters of the theory should include terms for interactions between like-charged ions. The equations developed are analogous to those in Pitzer's treatment of concentrated solutions, and the inclusion of ion-solvent interaction parameters allows comparison with the Stokes and Robinson hydration theory treatment. As with hydration theory, specific-interaction theory predicts differences in single-ion activity coefficients.     

The heat capacity of singly charged inorganic ions in methylpyrrolidone at 298.15 K

The standard partial molar heat capacities of singly charged ions in methylpyrrolidone (MP) at 298.15 K are reported. Heat capacity changes caused by the solvation of ions in MP and water are used to analyze the influence of various effects on ion-solvent interactions.     

Volumetric,rheological, and optical properties of hydroxylamine hydrochloride aqueous solutions containing NaCl,KCl, and NH4Cl at 30°C

Densities, viscosities, and refractive indices of aqueous solutions of hydroxylamine hydrochloride containing 0.05, 0.10, and 0.15 mol/dm³ NaCl, KCl, and NH₄Cl were measured at different concentrations of hydroxylamine hydrochloride at 30°C. Viscosity coefficients A and B representing ion-ion and ion-solvent interactions were determined from Jones-Dole equation. Experimental properties and viscosity coefficients have been interpreted in terms of ion-ion and ion-solvent interactions. Ion-solvent interactions were found to be dominating over the ion-ion interactions in studied systems.     

Variations of activity coefficients in concentrated electrolyte solutions at constant lonic strength

Measurements of different types on various (trace) electrolytes in HClO₄–Na(Li)ClO₄ solutions at several (constant) values of the ionic strength have been used to determine the variation of their activity coefficients with changing amount of perchloric acid in the solution. These variations (with respect to the hydrogen ion) differ considerably among different cations and anions. The results for the alkali metal ions and the anions are interpreted in the light of the recent work of Pitzer on short-range ionic interactions. The results for the cations with outerd-electrons and the alkaline earth metal ions are interpreted in terms of ion-solvent interactions. It is concluded that the use of HClO₄–NaClO₄ solutions of high ionic strength (rather than the use of HClO₄–LiClO₄ solutions) is advisable in studies where the variation in activity coefficients must be accounted for. Finally, it is shown that the usual interpretation of the influence of the salt medium in studies of complex equilibria and reaction kinetics is sometimes questionable.     

Ion-solvent interactions: Conductance behavior of NaAlBu4 and Bu4NAlBu4 in benzene and tetrahydrofuran

Conductance measurements are reported for NaAlBu ₄ and Bu ₄ NAlBu ₄ in benzene and in tetrahydrofuran (THF) from a concentration of approximately 5×10^?3 M to the fused state for each salt. This is the first reported study where a comparison of a salt with a small cation is made with one having a large cation in a noncomplexing solvent (benzene) and a complexing solvent (THF). The similarity in conductance behavior in THF and the differences in benzene are considered in terms of ion-ion and ion-solvent interactions.     

Application of Kirkwood-Buff theory to electrolyte solutions. III. Activity coefficients of aqueous NaCl between 273.15 and 573.15 K

Using a theory recently developed for the interpretation of activity coefficients of 1:1 electrolytes up to high concentrations in aqueous solution at 25°C, we have analysed available data for aqueous sodium chloride solutions up to saturation in the temperature range 273.15–573.15 K. The approach, which is based on Kirkwood-Buff theory and uses the truncated Poisson-Boltzmann equation to obtain the required information about the various ion-ion radial distributions, is able to fit the results to high accuracy with minimum of parameters, viz, three, of which one is the distance of closest approach, the other two relate to ion-solvent interactions and/or higher order terms in the ion-ion interaction.     

Ion-ion and ion-solvent interactions in lithium imidazolide electrolytes studied by Raman spectroscopy and DFT models

Molecular level interactions are of crucial importance for the transport properties and overall performance of ion conducting electrolytes. In this work we explore ion-ion and ion-solvent interactions in liquid and solid polymer electrolytes of lithium 4,5-dicyano-(2-trifluoromethyl)imidazolide (LiTDI)-a promising salt for lithium battery applications-using Raman spectroscopy and density functional theory calculations. High concentrations of ion associates are found in LiTDI:acetonitrile electrolytes, the vibrational signatures of which are transferable to PEO-based LiTDI electrolytes. The origins of the spectroscopic changes are interpreted by comparing experimental spectra with simulated Raman spectra of model structures. Simple ion pair models in vacuum identify the imidazole nitrogen atom of the TDI anion to be the most important coordination site for Li(+), however, including implicit or explicit solvent effects lead to qualitative changes in the coordination geometry and improved correlation of experimental and simulated Raman spectra. To model larger aggregates, solvent effects are found to be crucial, and we finally suggest possible triplet and dimer ionic structures in the investigated electrolytes. In addition, the effects of introducing water into the electrolytes-via a hydrate form of LiTDI-are discussed.     

Studies on the liquid junction potential corrections of electrolytes at aqueous + mixed solvent boundaries

Liquid junction potentials (E_J) generated at the boundaries of various salt bridge/mixed aqueous + organic solutions, have been determined by comparing the measured emf of silver cells with the calculated emf using literature values of transfer activity coefficients γ_t (Ag⁺) and γ_t (Cl⁻) based on the tetraphenylarsonium-tetraphenylborate (TATB) assumption.The E_J values have been analyzed in terms of the ion-solvent interaction, determined by ionic transfer Gibbs energies, and the so-called solvent-solvent interaction. The effect of varying the cation, anion, and concentration of bridge electrolyte, is assessed in aqueous acetonitrile (AN), ethanol (EtOH), and dimethylsulfoxide (DMSO). It is concluded that the previously reported solvent-solvent contribution to E_J is merely a correction factor to the ion-solvent interaction contribution due to solvent mixing at the boundary. Four salt bridges (sat. K₂SO₄ 3.5 M KCl, 3.5 M NaClO₄, and 0.1 M Et₄N-picrate) are compared on the basis of E_J.The recommended salt bridge for use with mixed aqueous + organic solutions is 3.5 M NaClO₄ in water. Appropriate E_J correction factors are presented for emf measurements in mixtures of AN + H₂O, EtOH + H₂O, and DMSO + H₂O.     

Dispersion self-free energies and interaction free energies of finite-sized ions in salt solutions

The role for many-body dipolar (dispersion) potentials in ion-solvent and ion-solvent-interface interactions is explored. Such many-body potentials, accessible in principle from measured dielectric data, are necessary in accounting for Hofmeister specific ion effects. Dispersion self-energy is the quantum electrodynamic analogue of the Born electrostatic self-energy of an ion. We here describe calculations of dispersion self-free energies of four different anions (OH-, Cl-, Br-, and I-) that take finite ion size into account. Three different examples of self-free energy calculations are presented. These are the self-free energy of transfer of an ion to bulk solution, which influences solubility; the dispersion potential acting between one ion and an air-water interface (important for surface tension calculations); and the dispersion potential acting between two ions (relevant to activity coefficient calculations). To illustrate the importance of dispersion self-free energies, we compare the Born and dispersion contributions to the free energy of ion transfer from water to air (oil). We have also calculated the change in interfacial tension with added salt for air (oil)-water interfaces. A new model is used that includes dispersion potentials acting on the ions near the interface, image potentials, and ions of finite size that are allowed to spill over the solution-air interface. It is shown that interfacial free energies require a knowledge of solvent profiles at the interface.     

Ion-Solvent Interaction of Biunivalent Electrolytes in Dioxane-Water Mixtures from Conductivity Data at Different Temperatures

This paper presents the conductivity measurements for some alkaline earth metal salts MgCl₂, MgBr₂, Mg(NO₃)₂, CaCl₂, CaBr₂ and Ca(NO₃)₂ by which the ion-solvent interactions are reported in the concentration range in dioxane-water mixtures at mass fraction of 0, 3, 10, 20 and 30% at 30°, 35°, 40° and 45°C ± 0.01. The conductance data were analyzed for the limiting molar conductivity, A_o, by the Fuoss-Edelson conductivity equation for the 2:1 unsymmetrical electrolytes. The results were discussed in terms of the solute-solvent interaction from the temperature coefficient of Walden product, Λ_oη of the electrolyte solutions. Moreover, Λ_oη was found to exhibit a linear relationship with the dielectric constant, ?, of the dioxane-water mixtures. The study gives information regarding the ion-solvent interactions from the mobilities and Walden product of the ions in the solvent. The ions appear to interact appreciably and the ion-solvent interaction tends to increase in the order Ca > Mg for the same anion while for the anions, the trend decreases in the order Cl^? < Br^? < No^?₃.     

The standard partial molar volumes of ions in N-methylpyrrolidone at 298.15 K

The standard partial molar volumes of electrolytes and ions in N-methylpyrrolidone (MP) at 298.15 K are presented. Separate components of ionic volumes in solutions in MP at infinite dilution, \(\overline {V_i^0 } \), are considered. The influence of various volume effects on ion-solvent interactions is analyzed.     

Activity coefficients of sodium,potassium, and nitrate ions in aqueous solutions of NaNO3, KNO3, and NaNO3+KNO3 at 25°C

Ion selective electrodes have been used to measure the activity coefficients at 25°C of individual ions in aqueous solutions of NaNO₃ up to 3.5 molal, KNO₃ up to 3.5 molal and mixtures of NaNO₃ and KNO₃ up to 2.4 molal total nitrate ion concentration. The experimental results confirm that the activity coefficient of anion and cation in aqueous single electrolyte solutions of NaNO₃ and KNO₃ were different from each other over the whole range of concentrations studied. These effects are attributed to the ion-ion and ion-solvent interactions. The results also show that the activity coefficients of nitrate ions in the presence of sodium and potassium counterions do not depend significantly on the nature of the counterions present in the solution. The experimental data obtained in this study were correlated by a model proposed previously.     

Thermodynamics of individual ions in ethylene glycol-water solvents

A new equation, correlating the cell (or electrode) potential with the dielectric constant of the solvent, has been developed and used to compute the chemical contribution to the transfer thermodynamic quantities of individual ions in various solvents. The results show that the electrostatic contribution to the transfer free energies should in fact account for all the interactions between the charge on the ion and the overall charge on the solvent molecules, of which the Born contribution plays but a minor role. The thermodynamic properties of individual ions have been discussed in the light of ion-solvent interactions as well as the structural effects of the solvents on the transfer process.     

The significance of large negative ions in the estimation of standard free enthalpies of transfer of single ions

The reliability of the method for the estimation of standard chemical free enthalpies of transfer of single ions, described previously, has been investigated further by the incorporation of data on the tetraethyl-, tetrapropyl- and tetrabutylboride ions. The studied solvents are the two phases of the n-butanol/water system. The data on the tetraalkylboride ions show that it is impossible to estimate single ion Δμ⁰ values for these solvents, with our present imperfect state of knowledge of solvation of ions. The main imperfections are probably the crudeness of current electrostatic models, and the common neglect of specific ion-solvent interactions.     

Effect of Solvents on the Corrosion Inhibition of Copper by 1,2,3-Benzotriazole

Electromotive force (E) measurements have been made at 303.15 K on the cell, Cu _x Hg/CuCl₂ (m) in solvent S′ [S′=W or FD or DMF each containing 15 ppm of 1,2,3-benzotriazole (BTA)] /AgCl/Ag (where W, FD and DMF represent the solvents water, formamide and N,N-dimethylformamide, respectively). The Emf data have been compared with the corresponding data under the same conditions in pure W, FD and DMF; the Emf values change from negative to very positive in the presence of BTA in these solutions and suggest the possibility that the presence of BTA in W, FD and DMF helps to bind copper ions with solvent molecules through formation of new complex structures of the film formed on the metal surface. We have suggested the probable mechanism of formation of a protective film through complex formation. The higher Emf values in the presence of BTA indicate strong ion-solvent interactions and the order of interactions was found to be as: FD≥DMF>W. Further iterative procedures were employed to evaluate K ₁,K ₂ (dissociation constants), α ₁,α ₂ (degrees of dissociation), γ _± (mean activity coefficient) and E ^o (standard cell potential) making use of the measured E values. The standard molar Gibbs energy of transfer, ΔG _tr^o, of CuCl₂ from the pure S to S′ were calculated using the computed standard cell potentials. The calculated ΔG _tr^o values were found to be negative which was indicative of strong ion-solvent interactions and reasonably supported the trend of ion-solvent interactions. From these studies we concluded that BTA acts as a better corrosion inhibitor towards copper in FD and DMF than water.     

Thermochemical parameters of Ni(NO3)2 solutions in water + formamide + α-alanine mixtures at 298 K

The enthalpies of mixing of aqueous solutions of nickel(II) nitrate in water + formamide + α-alanine mixtures in the range of existing amide concentrations have been measured calorimetrically. From these data the standard enthalpies of electrolyte transfer from water into ternary mixtures have been calculated. The type and character of electrolyte transfer isotherms are discussed on the basis of the heats of transfer of individual ions that were studied earlier, as well as the contributions into these values that characterize structural changes in the solution and chemical ion-solvent interactions.