Alkali halide solutions

Clever, H.L. Holland, C.J. "Solubility of Argon Gas in Aqueous Alkali Halide Solutions — Temperature Coefficient of the Salting Out Parameter," J. Chem. Eng. Data, 1968, 13, 411-14. 

Ion-pair formation is more clearly seen in cesium halide solutions than in other alkali halide solutions discussed previously, because of weak hydration of cesium ions. The formation of contact ion pairs between Cs+ and F ions has been suggested by Szasz and Heinzinger (33) in 2.2 mol dm-3 aqueous solution. 

Fig. 8. The Linear Variation of the Logarithm of the Activity Coefficient of Hydrochloric Acid in Alkali Halide Solutions at a Constant Total Molality of...

Masuda, M. Yoshida and A. Kashiwada, Electrolysis method of alkali halide solution,... 

Table 5 presents the results of In fi determinations in relation to the concentration of some alkali halides and urea at 25 °C. Based on the assumption that the free (or bulk ) water in aqueous solutions is identical with pure water, the fractionation factor between the free water molecules in solution and water vapor or between that and hydrogen gas, Q f v or df-g, should be equal to that between pure water and water vapor or between that and hydrogen gas, Wpw-v or ttpw-g, respectively. Then the negative value of the In/S for alkali halide solutions indicates that the fractionation factor between hydrated water and the free water in solution, ah-f,... 

Dielectric relaxation times in aqueous alkali halide solutions were obtained by Kaatze et al. (Giese et al. 1970 Wen and Kaatze 1977 Kaatze 1997) from the complex permittivities as a function of the frequency. The relaxation data were analyzed by Kaatze (1997) in terms of the ratios of the cooperative reorientation times tqi of water molecules hydrating the ions in 1 M solutions to that. Tew = 8.27 0.02 ps, of pure water at 25 °C. Individual ionic values are based on setting the values for K+ and Cl as equal. The ratios rei/rew are shown in Table 3.2, and are seen to follow the pattern shown in Table 3.1, namely, that structure-breaking ions have tei/tew < 1 and structure-making ones have Tei/reww > 1-... 

Cationized molecular ions can easily be formed through the addition of a few microliters of a dilute alkali halide solution to the sample/matrix solution on the FAB probe tip. Addition of lithium, sodium or potassium produces [M -b cation] ions with corresponding shifts of 6,22 and 38 daltons compared with the mass of the protonated molecular ion [M-bH]. In some samples higher mass species are observed, owing to the incorporation of additional cations through cation/ hydrogen exchange reactions. 

Fennell CJ, Bizjak A, Vlachy V, Dill KA (2009) Ion pairing in molecular simulations of aqueous alkali halide solutions. J Phys Chem B 113 6782-6791... 

This ST2 model was employed in the earlier series of MD simulations of aqueous alkali halide solutions (Heinzinger and Vogel 1976). Evans (1986) later proposed a modification of the ST2 potential which included atom-atom LJ terms centered both on the oxygen and hydrogen atoms, thus eliminating the need to use the switching function. This model has been employed in MD simulations of water at temperatures up to 1273 K and at constant densities of 1.0 and 0.47 g/cm (Evans et al. 1988) and has shown, within the statistical uncertainty, a satisfactory reproducibility of the experimental pressure in this range and at the critical point of water. 

In our discussion of halide ion quadrupole relaxation we will follow a path of increasing complexity of the systems. First, we consider in the following subsection the relaxation rates observed for the ions at infinite dilution in water and in connection with this the theoretical treatment of relaxation due to ion-solvent interactions. In Subsection 5.1.3, experimental data for aqueous solutions of alkali halides are considered and in connection with this we outline theoretical attempts to account for effects of ion-ion interactions on the relaxation rates. Apart from alkali halide solutions few inorganic systems, mainly earth alkali halide solutions, have been studied and these are treated in Subsection 5.1.4. Hydrophobic solutes have particularly strong effects on chloride, bromide and iodide relaxation and the explanation to this is considered in Subsection 5.1.5. Long-chain hydrophobic solutes in aqueous systems form various types... 

This survey of the experimental concentration dependences around 25°C of halide ion quadrupole relaxation rate for aqueous alkali halide solutions can be summarized in the following general conclusions drawn from Figs. 5.1 - 5.3, which probably constitute the most... 

Fig. 5.4. Ionic contributions to the 3 C1", Br and 1271-relaxation rates in aqueous alkali halide solutions at 25 C. For the definition and calculation of A, see text and Ref. [248, from where the figure is taken...

In Ref. [261] Hertz and co-workers make a similar analysis for the alkali ion relaxation in aqueous alkali halide solutions and. 

As is evident from our discussion, considerable efforts have been made to theoretically rationalize the ion-ion contributions to ion relaxation in aqueous alkali halide solutions, and in particular to discriminate between electrostatic and electronic distortion contributions. However, the problem has shown to be of such a complexity that although significant progress has been made in recent years we are still far from the final answer. It may in this connection be illustrative to compare alkali ion effects on halide ion quadrupole relaxation with some other properties. We have seen that - although the relative effects change with concentration - the sequences k <... 

The relaxation rates vary more strongly with temperature than do the halide ion relaxation rates of aqueous alkali halide solutions [303 305 306], The apparent energy of activation of the relaxation process increases with increasing substitution on the nitrogen for aqueous solutions of substituted alkylammonium bromides [303], Activation energies of bromide relaxation are included in Table 5.2. 

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