The changes in free energy, enthalpy and entropy for the formation of uranyl(Vl)-thioglycolate, thoriùm(Iv)-gÌycolate and -thioglycoÌate complexes have been determined. The changes in free energy were calculated from the stabilìty constants, obtained from a potentiometric determination of the concentmtion of free hydrogen ion, using a glass or quinhydrone electrode. The enthalpy values were measured calorimetrically. The measurements were perfoÌmed at 25.0.C in an aqueous sodium perchlorate medium with the total sodium concentration equal to 1.00 M. A compari_ son of the magnìtude of the enthalpy and entropy changes for the various systems gives additional support of the view that the thioglycolate acts as a monodentate Iigand while the glycolate forms chelate rings.
Thermodynamic properties of actinide complexes. Part V: Uranyl(IV)-thioglycolate system, thorium(IV)-glicolate and thioglicolate systems.
DI BERNARDO, PLINIO;MAZZI, ULDERICO;
1978
Abstract
The changes in free energy, enthalpy and entropy for the formation of uranyl(Vl)-thioglycolate, thoriùm(Iv)-gÌycolate and -thioglycoÌate complexes have been determined. The changes in free energy were calculated from the stabilìty constants, obtained from a potentiometric determination of the concentmtion of free hydrogen ion, using a glass or quinhydrone electrode. The enthalpy values were measured calorimetrically. The measurements were perfoÌmed at 25.0.C in an aqueous sodium perchlorate medium with the total sodium concentration equal to 1.00 M. A compari_ son of the magnìtude of the enthalpy and entropy changes for the various systems gives additional support of the view that the thioglycolate acts as a monodentate Iigand while the glycolate forms chelate rings.
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