Thermodynamic characteristics of complex formation in the zinc(II)-glycylglycine system in aqueous solution
作者:L. A. Kochergina、O. M. Drobilova
DOI:10.1134/s0036023610050177
日期:2010.5
The heats of reaction of zinc(II) with glycylglycine at temperatures 288.15, 298.15, and 308.15 K and ionic strengths 0.25, 0.50, and 0.75 (potassium nitrate as a supporting electrolyte) were determined by calorimetry. The thermochemical results were processed with inclusion of stepwise equilibria. In addition to complexation reactions, "side" protolytic processes were considered. Standard heats of complexation in the system were found by extrapolation to the zero ionic strength by an equation with one individual parameter. The influence of the supporting electrolyte concentration and temperature on the thermodynamic characteristics of the complexation reactions in the glycylglycine-zinc(II) system was considered. The standard enthalpies of formation of ZnGlyGly(+), Zn(GlyGly)(2), and Zn(GlyGly) (3) (-) species in aqueous solution were calculated.