The Salting-in Effect, Calculation of Activity Coefficients and Determination of Gibbs Transfer Functions of K+, Ba2+, [Co(bpy)3]2+ a [Co(bpy)3]3+ in Water-Acetonitrile Mixtures

Page: 411

J. Benkoa, O. Vollárováa, M. Aranyosiováa, and A. Baldb

a Department of Physical and Theoretical Chemistry, Faculty of Science, Komenský University, Bratislava, Slovak Republic, b Department of Didactics of Chemistry, Faculty of Chemistry and Physics, University of Łodź, Łodź, Poland


Solubilities of K, Ba and tris(2,2'-bipyridine)cobalt(3+) picrates in water and aqueous sodium nitrate were measured and their activity coefficients were determined from the solubility dependences on ionic strength. By comparing experimental and theoretical results it was found that the extended Debye-Hückel relation is appropriate for calculation of activity coefficients of the salts in the ionic strength range I=0−0,5 mol dm−3. Gibbs transfer functions of the ions were calculated from the salt solubilities in water-acetonitrile mixtures using an extrathermodynamic presumption. In the case of [Co(bpy)3]2+ and [Co(bpy)3]3+, the hydrophobic nature of ligands has a decisive influence on change in solvation. The experiments are included in advanced practical training in physical chemistry.


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