Abstract
The polarograms of Cd(II) in 0.15M tartrate solution were investigated in the range of pH values from 6.0 to 12.6 at 20$^{\circ}and 25$^{\circ}C. Up to pH value of 7.8, the limiting current and the halfwave potential were found to be constant, and when compared with the nitrate solution of the same $Cd^{++}$ concentration at the same ionic strength, the limiting current decreased by 28% and the halfwave potential shifted by -0.05 volt. The values of limiting current sharply decreased as the pH value exceeded 8.2 and the minimum values appeared at the pH values of 11.2~11.4. The values of halfwave potential gradually decreased as the pH value increased over 8.2 and the value of -0.78 volt was obtained at the pH value of 12.6. Possible mechanisms of electrode reaction were suggested and the anomalous behavior of reduction waves of Cd(II) in tartrate solution up to pH value of 9.4 was discussed.
pH 6.0~12.6 範圍에서 0.15M 타르타르酸鹽支持溶液 속에서의 Cd(II)플라로그람을 20$^{\circ}C 및 25$^{\circ}C에서 調査한 結果 pH 7.8 部分까지는 限界電流값 및 半波電位값이 一定하지만 같은 이온强度의 窒酸鹽支持溶液을 사용하였을 때에 비하여 半波電位값이 0.05 volt 負쪽으로 移行하고 있으며 限界電流값은 28% 감소되었다. pH 8.2 部分以上부터는 限界電流값이 急激하게 감소하다가 pH11.2~11.4 부근 以上부터 다시 急激히 증가하는 現象을 보여 주었다. 한편 pH 8.2 部分以上부터는 半波電位값은 pH증가에 따라 계속 負 쪽으로 移行하여 pH 12.6에서는 -0.78volt로 되었다. 可能한 電極反應機構를 假定하고 pH 9.4에 이르기 까지의 還元波變動의 原因을 檢討하였다.