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Dielectric relaxation of aqueous Na2CO3 solutions

Capewell, S.G., Buchner, R., Hefter, G. and May, P.M. (1999) Dielectric relaxation of aqueous Na2CO3 solutions. Physical Chemistry Chemical Physics, 1 (8). pp. 1933-1937.

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The complex dielectric permittivity of aqueous sodium carbonate solutions (0.05 ≤ c/mol L-1 ≤ 2.5) has been determined in the frequency range 0.2 ≤ v/GHz ≤ 20 at 25.0 °C with a commercial dielectric measurement system based on a vector network analyser. A superposition of three Debye relaxation processes was necessary to fit the complex permittivity spectra. The slow and intermediate dispersion steps are assigned to double solvent separated (2SIP) and solvent-shared (SSIP) NaCO3-(aq) ion-pairs respectively. The absence of contact ion-pairs was confirmed by Raman spectroscopy. The fast process is assigned to the collective relaxation of the solvent. Equilibrium constants for the formation of NaCO3-(aq) were determined from the ion-pair dispersion amplitudes. The effect of Na2CO3 concentration on the water dispersion amplitude allowed effective solvation numbers to be deduced.

Publication Type: Journal Article
Murdoch Affiliation: School of Chemical and Mathematical Science
Publisher: Royal Society of Chemistry
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