A SPECTROELECTROCHEMICAL STUDY OF A 2ND-ORDER CATALYTIC PROCESS INVOLVING SULFITO-COPPER(II) COMPLEXES

A spectroelectrochemical study has been performed using indium tin oxi de glass as the working electrode in order to obtain kinetic parameter s of the reaction 2Cu(II) (SO3)(n)((2n-2)-)+2SO(3)(2-) --> 2Cu(I)(SO3) (n)((2n-1)-)+S2O62- which is involved in the copper-catalyzed oxidatio n of sulfite. The absorbance at 370 nm due to sulfito-copper (II) comp lexes has been measured in single and repeated current pulse experimen ts. A signal-averaging technique has been developed in the case in whi ch the absorbance is not zero at the beginning of each pulse. The resu lts have confirmed that the reaction is of the second order with respe ct to Cu(II). The rate constant and the molar absorptivity of copper( II)complexes have been obtained.