The enthalpies of interactions of Ca2+(aq) and C2O 4 2− (aq) ions in complexon solutions: Competition between complexation and precipitation

Autor: Andrey V. Kustov, V. N. Trostin, Nataliya L. Smirnova, Berezin Boris D
Rok vydání: 2010
Předmět:
Zdroj: Russian Journal of Physical Chemistry A. 84:588-592
ISSN: 1531-863X
0036-0244
DOI: 10.1134/s0036024410040126
Popis: The thermal effects of mixing of aqueous calcium chloride with sodium citrate and ethylenedi-aminetetraacetate in the absence and presence of sodium oxalate have been measured at 25°C. The thermal effects of dilution of aqueous calcium chloride solutions were determined. The thermal effects of calcium oxalate precipitation and formation of calcium complexes with citrate and ethylenediaminetetraacetate ions were calculated. The 1% solution of sodium citrate inhibited the formation of CaC2O4 (s); in a 1% solution of sodium ethylenediaminetetraacetate with [Ca2+][C2O 4 2− ] > 10−5, the endothermal formation of the [CaEdta]2− complex quickly changed to exothermal precipitation. The 3 and 5% solutions of complexons showed a pronounced inhibiting effect on the formation of urinary stones even when the concentration of calcium and oxalate ions in solution exceeded the product of solubility of CaC2O4 by four and more orders of magnitude.
Databáze: OpenAIRE
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