KINETIC AND MECHANISTIC STUDY OF THE COPPER(II)-OXAMATE COMPLEXATION,MONITORED BY THE CU-II SOLID-STATE ION-SELECTIVE ELECTRODE

The complexation process of copper(II) with oxamates was followed by t he use of a copper solid state ion selective electrode. The shape of t he recorded potential vs. time was interpreted on the basis of the kno wn kinetic expressions for a two step reaction, monitoring the consump tion of the reagent. The potential changes of the electrode are attrib uted to a decrease in the copper concentration. The curves are of an e xponential form with two distinct parts, the first due to the intermed iate activated complex, which is produced very rapidly, and the second is due to the slow formation of the soluble chelate. The effects of v arious parameters are studied in relation to the retardation of the fi rst step. The reaction rate constant k, the equilibrium constant K- f or the fist step, the stability constant K, the activation energy E(a) , the change in enthalpy, and the product (pZ) of the frequency and st eric factors were determined. On the basis of the above data, a mechan istic scheme for this complexation reaction is proposed.