STUDY OF COORDINATION EQUILIBRIA IN SYSTEMS OF COEXISTING MONONUCLEARAND POLYNUCLEAR COMPLEXES BY AN ISOSBESTIC POINT SPECTROPHOTOMETRIC METHOD

This paper reports a method for determining the stability constants of complexes in a system of coexisting mononuclear and polynuclear compl exes based on analysis of dual isosbestic points. First it is necessar y to determine the dissociation degrees of either of the two complexes concerned in two directions, and then their stability constants. With this method, the conditional constant can be evaluated by appropriate treatment and selection of the proper equations for solutions. For de monstration purposes the scandium/Xylenol Orange system was used to te st the model and satisfactory results were obtained.