Zusammenfassung
A systematic study of the dielec. relaxation spectra of aq. solns. of NaBr, NaI, NaNO3, NaClO4, and NaSCN was made over a wide range of frequencies (0.2 ≤ ν/GHz ≤ 89) and solute concns. (0.05 ≤ c/M ≤ 1.5) at 25°. The spectra could be adequately described by a single Cole-Cole (CC) process, sym. broadened relative to that of pure water. However, similar quality fits were also obtained with a ...
Zusammenfassung
A systematic study of the dielec. relaxation spectra of aq. solns. of NaBr, NaI, NaNO3, NaClO4, and NaSCN was made over a wide range of frequencies (0.2 ≤ ν/GHz ≤ 89) and solute concns. (0.05 ≤ c/M ≤ 1.5) at 25°. The spectra could be adequately described by a single Cole-Cole (CC) process, sym. broadened relative to that of pure water. However, similar quality fits were also obtained with a three-Debye-process (3D) model consisting of a small ion-pair contribution at lower frequencies and two solvent relaxations at higher frequencies. Assuming the ions to be solvent sepd., the 3-dimensional model provided ests. of their assocn. consts. and their rate consts. for formation and dissocn. The bulk water relaxation times obtained from both models showed almost no dependence on the nature of the anion. Nevertheless, there were subtle differences in the concn. dependences of the relaxation times which correlated with some, but not all, of the anion properties that are believed to be relevant for explaining the anionic Hofmeister series.
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