Conductometric study of association phenomena of some metal(II) complexes in water at different temperatures

Abstract

The association constants, K_A, for Mg, Ca, Sr and Ba salts of acetate, propionate and butyrate have been determined at 25, 35, 45 and 55 °C in aqueous solutions using the conductometric technique; the data were treated by the Lee and Wheaton method. K_A tends to increase with atomic number in the order Mg < Ca < Sr < Ba for all the systems under study. While for the ligands, K_A tends to increase in the order acetate < propionate < butyrate. Thermodynamic parameters, ΔH and ΔS, for ion-pair formation of all the salts were obtained and discussed. The thermodynamic metal gradient, β, was derived and the thermodynamic characteristics of ion-pair formation of all systems were discussed. Also, Walden products, Λ_oη, were determined and discussed.