Dependence of the enthalpies of formation of Ag+ complexes with glycinate ion and the protonation of glycinate ion on the content of aqueous ethanol solvent
Enthalpy changes are determined by calorimetry for the reactions of glycinate ion (Gly−) proto- nation and its complexation with Ag+ ion at a temperature of 298 K and ionic strength 0.1 (NaClO4) in an aqueous ethanol solvent containing 0.0–0.4 and 0.0–0.3 mole fraction of alcohol, respectively. An abnormal relationship of enthalpy changes is found for the processes of stepwise formation of mono- and bis-glycinates of silver(I) in water. It is shown that varying the ethanol content has virtually no effect on the exothermicity of Ag+ complexation reactions with glycinate ions at either coordination step and does not change the relationship of the step enthalpies. An analogy is observed in the relationship of solvation contributions from the reagents to the value of ΔtrH° for the reactions of glycinate ion protonation and its complexation with silver(I) in aqueous ethanol solvents.