Diffusion coefficients of Cd++ and Co++ at 20 degrees Celcius by polarography.

Abstract

The limiting diffusion coefficients of Cd++ and Co++ at 20°C, determined from concentration overvoltage at a dropping mercury electrode, are (6.08 + 0.09) X10^-6 cm^2 sec^-l and (6.28 + 0.17) X10^-6 cm^2 sec^-1, respectively. The apparent diffusion coefficients of Cd++ and Co++ in the supporting electrolytes used, NaN03 and Na2S04, decrease as the ionic strengths and the viscosities of the solutions increase. A plot of the apparent diffusion coefficient of either Cd++ or Co++ at zero concentration of the supporting electrolyte as a function of the concentration of Cd++ or Co++, under the experimental conditions, has a positive slope.