Chemical speciation of oxalato complexes of indium(III)

Abstract

Chemical speciation of binary complexes of indium(III) with oxalic acid has been investigated pH metrically at 303 K and at an ionic strength of 0.2mol dm-3. The approximate formation constants have been calculated with the computer program SCPHD utilizing the experimental data obtained by monitoring H+ ion concentration. The formation constants thus obtained are refined with the computer program, MINIQUAD75 using primary alkalimetric data. The selection of the best-fit chemical model is based on the statistical parameters and residual analysis. The major complexes formed are In(C2O4)2-, In(C2O4)33-, [In(C2O4)2OH]2- and [In(C2O4)2 (OH)2]3-. The distribution patterns of the different species with the pH values showed that In(C2O4)2- is the predominant species.