Kinetics of oxidation or CU (II) in basic solutions of dimethylglyoxime by persulfate ion.

Abstract

This thesis describes investigations into the kinetics of the color reaction which occurs when CU(II) in unbuffered basic solutions of dimethylglyoxime is oxidized by persulfate solution. The color change accompanying the reaction was monitored by a dipping-probe colorimeter at wavelength of 520 nm. A double-injection technique was developed in order to improve the reproducibility of experimental results. The concentration of CU(II) was kept in the vicinity of 5X10(-5) mol/L while those of Na2dmg and K2S2O8 were usually around 5X10(-4) mol/L. The production of the pink color was found to be half order with respect to K2S2O8 for concentrations below about5X10(-4) mol/L and first order with respect to Cu(II) for concentrations up to about 8X10(-4) mol/L (i.w. Na2dmg/Cu(11) ratio in excess of 5:1). The dependence of the reaction rate on the hydrogen ion concentration could not be established with certainty. These results suggest that the rate determining step of the reaction is a one-electron transfer reaction betwen the SO radical and the CuII (Hdmg). comples