The Transference Numbers of Potassium Bromide in Aqueous Solution at 25°C

Abstract

The transference numbers for aqueous solutions of potassium bromide at 25°C have been determined by the moving boundary method. Cells with cadmium bromide and lithium bromide as cation indicators and with potassium iodate as anion indicator were employed. The measurements are more difficult than with potassium and sodium chlorides; with sheared junctions, a thorough investigation of the effect of indicator concentration is necessary for each solution studied, and the same is true with both sheared and autogenic boundaries of the effect of current density. The results differ slightly from those previously reported by Longsworth, but are consistent with the known value of t+0. Potassium bromide also differs from the alkali chlorides and acetates in that the Longsworth function t+0′ is not linear in the concentration, thus precluding an independent extrapolation of the transference data.