Some studies of electrolyte solutions in liquid ammonia: the determination of the transference numbers of some univalent cations at various temperatures

Abstract

In this work an experimental accuracy to give results which can be taken as accurate to better than one part in 1000 has been aimed at, and, in order to make some comparisons between cations, in the absence of all the relevant salt conductance data, the work has been carried out using nitrate solutions. A method using an "autogenic" boundary (6,34) has been devised as this avoided the enormous practical problem which would have been created in attempting to set up a "sheared" boundary (35). Mercury was chosen as the anode metal as it can be poured into the sealed tube of the transference cell, freezes to form a good seal in the tube and electrolyses to form the soluble mercuric nitrate which acts as the indicator electrolyte. Silver was the other metal which was seriously considered for the purpose but it was found to be difficult to obtain a neat silver to glass fit when the system was to be used some 60 to 80 C. degrees below the ambient temperatures, as the two materials have different coefficients of expansion.With experience which has been gained in the course of this work it is hoped that a much more accurate determination of the transference number of the K+ ion in potassium iodide solution in liquid ammonia will be possible to provide a standard upon which accurate single ion conductance data can ultimately be based.