Investigation of Magnesium (II), Calcium (II) and Barium (II) Complexes in Aqueous Solution
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The ionic association constants, K6, of Mg, Ca and Ba metal ions with succinate, malate and tartrate ligands were conduct metrically determined in water at 25-40°C. The conductometric data were analysed by the Shedlovsky extrapolation method. The KE values tend to decrease with the cation size in the order Ca > Ba for all the salts under study with the exception of Mg salts, whereas the KA values for the ligands increase in the order succinate < malate < tartrate. poi the salts under study, standard thermodynamic functions, AH° and AS" for the association, were evaluated and discussed. The positive values of both AH" and AS' in all the systems indicate the ionic association processes are the reactions of unfavorable enthalpy and favorable entropy changes in aqueous solution. The thermodynamic metal gradient, B, was evaluated and its significance of ion association of all salts under investigation was discussed. On the other hand, the results of limiting molar conductancs, Ao, are discussed on the light of Walden product.