The Variation of the Transference Numbers for Calcium Chloride in Aqueous Solution with Temperature. III

Abstract

Transference numbers for calcium chloride in aqueous solution have been determined for concentrations up to 0.15N at 15°, 25°, and 35°C. At all three temperatures autogenic cation boundaries using cadmium chloride as indicator gave transference numbers which showed no progression as the boundary moved and were independent of current. The same was true of anion boundaries (employing calcium iodate and paratoluene sulphonate as indicators) at 25°C provided the concentrations of the indicator ions were held within rather narrow limits. Where both t+ and t− were determined for a solution, their sum was unity within the precision of the measurements. These results differ, however, from Longsworth's data by somewhat more than the apparent precision of the measurements. The variation of the transference numbers with temperature is normal in that they tend to approach one-half with increasing temperature. As in the case of sodium chloride, the variation of the transference number with concentration is independent of the temperature.