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Ion-pair and solvent relaxation processes in aqueous Na2SO4 solutions

Buchner, R., Capewell, S.G., Hefter, G. and May, P.M. (1999) Ion-pair and solvent relaxation processes in aqueous Na2SO4 solutions. Journal of Physical Chemistry B, 103 (7). pp. 1185-1192.

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The complex dielectric permittivity of aqueous sodium sulfate solutions (0.025 ≤ c/mol dm-3 ≤ 1.6) has been determined in the frequency range 0.2 ≤ ν/GHz ≤ 20 with a commercial dielectric measurement system based on a vector network analyzer. The spectra were supplemented with interpolated literature data at 12 ≤ ν/GHz ≤ 89. To fit the complex permittivity spectra, a superposition of three Debye relaxation processes was necessary. The slow and intermediate dispersion steps are assigned to the tumbling motion of doubly solvent-separated (2SIP) and solvent-shared (SSIP) NaSO4- ion pairs, respectively. The fast process, of amplitude S3, is due to the collective relaxation of the solvent. Effective solvation numbers were deduced from the effect of Na2SO4 concentration on S3. From the ion-pair dispersion amplitudes, S1 and S2, the concentrations c2SIP and cSSIP, and thus the overall stoichiometric stability constant, βNaSO4-, were determined

Item Type: Journal Article
Murdoch Affiliation(s): School of Chemical and Mathematical Science
Publisher: American Chemical Society
Copyright: © 1999 American Chemical Society.
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