Mixed Alkali Halide Solutions

In attempts to further elucidate the detailed relaxation mechanism and in particular to investigate the significance of higher ion-ion correlations, experiments with aqueous solutions containing two alkali halides should be helpful. This possibility has not yet been systematically investigated but the two reports given [258 261] provide interesting results. 

Hertz [258] studied the Br relaxation in solutions containing KBr and another potassium salt which was KF, KCl, KI, KOH or KNO. Substitution of f or 0H ions for part of the Br ions gives a small 

Also in a recent paper [261] Hertz et al, find no change in Br relaxation rate when l is gradually substituted for Br. The alkali ion was now Cs or Na. Furthermore, for mixed solutions of 

Thus for example, in solutions containing RbCl and RbBr, with a con- 

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EXAFS studies on tris-maltolatoiron(III) in the solid state and in solution, and on [Fe(Ll)3] hydrate, pave the way for detailed investigation of the hydration of complexes of this type in aqueous media.Solubilities and transfer chemical potentials have been determined for tris-maltolatoiron(III) in methanol-water, and for tris-etiwlmaltolatoiron(III) in alcohol-water mixtures and in isobutanol, 1-hexanol, and 1-octanol. Solubility maxima in mixed solvents, indicating synergic solvation, is relevant to trans-membrane transport of complexes of this type. Solubilities of tris-ethylmaltolatoiron(III) and of [Fe(Ll)3] have been determined in aqueous salt solutions (alkali halides NH4 and NR4 bromides). ... 

The densities and volumetric specific heats of some alkali halides and tetraalkylammonium bromides were undertaken in mixed aqueous solutions at 25°C using a flow digital densimeter and a flow microcalorimeter. The organic cosolvents used were urea, p-dioxane, piperadine, morpholine, acetone, dime thy Isulf oxide, tert-butanol, and to a lesser extent acetamide, tetrahydropyran, and piperazine. The electrolyte concentration was kept at 0.1 m in all cases, while the cosolvent concentration was varied when possible up to 40 wt %. From the corresponding data in pure water, the volumes and heat capacities of transfer of the electrolytes from water to the mixed solvents were determined. The converse transfer functions of the nonelectrolyte (cosolvent) at 0.4m from water to the aqueous NaCl solutions were also determined. These transfer functions can be interpreted in terms of pair and higher order interactions between the electrolytes and the cosolvent. 

In recent years we have undertaken a systematic investigation of the volumes and heat capacities of transfer of alkali halides and tetraalkylammonium bromides from water to mixed aqueous solvents (1-6). These properties are important because, when combined with enthalpies and free energies, they can be used to calculate the temperature and pressure dependences of various equilibrium properties of electrolytes in mixed solvents. Since the properties of electrolytes in mixed aqueous solvents are closely related to the corresponding properties of the nonelectrolyte in an electrolyte solution, infor-... 

Only occasionally have salt molecules been vaporized for use as a reactant toward another species in matrix isolation studies. Devlin (24,25,26) conducted extensive experiments in which salt molecules were vaporized and condensed into argon matrices containing from 1% to 90% H2O or NH3, to study the effects of stepwise solvation of the salt molecule, as a model for solution studies. Margrave (27 ) and Snelson (28) each have used salt molecules as reactants, but most commonly toward another salt molecule to form a mixed salt dimer. The work described below, which was initiated at the University of Virginia and has been continued at the University of Cincinnati, employs alkali halide salt molecules as reactants toward a variety of species, including both Lewis acids and Lewis bases. The initial intent was to react a salt molecule such as NaCl with HCl in an excess of argon to bring... 

These various silver halides are usually precipitated in batch or continuous reactors by mixing aqueous solutions of alkali halide salts and silver nitrate. One, two or more reagents may be pumped into the reactor under programmed or feedback control. Key control variables are reagent mixing and delivery, temperature, and especially silver ion activity. The latter can be electrochemically monitored by using silver or silver salt electrodes, and the relative potentials measured by such electrodes provide a means to impose feedback control... 

Double decomposition is the usual way of forming sols of insoluble salts Silver halides easily give colloidal solutions by mixing of silver nitrate and alkali halide solu-> tions. A sol of arsenic trisulphidc is obtained by introducing hydrogen sulphide into a saturated solution of arsenic trioxidc ... 

In general, hydrated borates of heavy metals ate prepared by mixing aqueous solutions or suspensions of the metal oxides, sulfates, or halides and boric acid or alkali metal borates such as borax. The precipitates formed from basic solutions are often sparingly-soluble amorphous soHds having variable compositions. Crystalline products are generally obtained from slightly acidic solutions. 

The osmotic coefficients calculated from Eq. (9) can be brought into good agreement with solution data up to about 1M for aqueous solutions of alkali (26) and alkaline earth halides, (30) tetraalkyl ammonium halides, T3l) mixed electrolytes, where the Harned coefficients are measured, (32) and electrolyte-non electrolyte mixtures, where Setchenow coefficients are measured. 

Tin(IV) oxide is amphoteric and dissolves in aqueous acids or alkali solutions. The predominant tin species in appropriate acid solutions are of the type [SnXe], where X = halide or pseudohalide, and also mixed anions [SiiX Xg ]2 (e.g. X, X = halides or pseudohalides). 

It is obvious from the foregoing discussion that the enthalpies of mixing for charge-unsymmetrical systems do not follow the simple conformal solution theory. When the anion in a strontium halide-alkali metal halide mixture from chloride to bromide and from bromide to iodide is changed, the enthalpy of mixing is decreasing. For all systems, the enthalpy interaction parameter, k, is a linear function of 512 with the usual exception for lithium-containing systems. Two important features of the k versus 512 plot should be emphasized ... 

R. Kiyono, Y. Asai, Y. Yamada, A. Kishihara and M. Tasaka, Anomalous water transport across cation-exchange membranes under an osmotic pressure difference in mixed aqueous solutions of hydrochloric acid and alkali metallic halide, Seni Gakkaishi, 2000, 56, 298-301 M. Tasaka, T. Okano and T. Fujimoto, Mass transport through charge-mosaic membranes, J. Membrane Sci., 1984,19, 273-288. 

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