Abstract
When copper chloride was added to an aqueous ascorbic acid solution and the behavior of copper inons was polarographed, it was found that the half-wave potential of the copper ions was -0.14 V vs. SCE. It is thougt that the Cu^<2+> is first reduced to Cu^+ and then chelate comounds are formed. The UV spectrum of the sample showed absorption banbs at λ^<H_2O>_<max> 720 mμ and 798 mμ, and in contrast to the UV spectrum of ascorbic acid (λ^<H_2O>_<mex> 245 mμ) it had shifted toward much longer wave lengths. A study of the electron transition mechanism was made when a copper chelate compund of ascorbic acid is formed and this shows that activity coefficients (kf_0) will be 3.02×10^<-3> for pH 6,3.27×10^<-3> for pH 8,and 2.83×10^<-3> for pH 9. No significant changes can be observed in the activation energy and activation entropy obtained from these activity coefficients for the samples at an electrolyses temperature of 25℃. This implies that during activation in the electric field of the electrode the contributing effect of induced dipole efficiency is greater than that of permanent dipole efficiency of the chelate itself. Because ascorbic acid is oxidized by the copper ions and dehydroascorbic acid forms copper chelate compounds, a phenomenon will be observed in which the characteristic absorption band on the UV spectrum shifts toward the visible region and the half-wave potential of Cu^+ becomes positive simultaneously.
