Zur Deutung von Hittorfschen Überführungsversuchen bei Elektrolytschmelzen mit drei ionischen Bestandteilen / Interpretation of Hittorf Transference Experiments in Ionic Melts with Three Ion Constituents

Abstract

For an ionic melt, consisting of three ion constituents, the relation between internal and effective transport numbers is established. The interpretation of Hittorf transference experiments in terms of the two kinds of transport numbers is given. It is shown that the usual experimental procedures lead to the internal transport numbers which only depend on the properties of the melt. The effective transport numbers, depending on the boundary conditions of the experiments, can be calculated from the internal transport numbers and from density data. Thus there is only one independent transport number. The ionic melt LiNO3+AgNO3 at 260 °C is taken as an example. Here the internal transport numbers of Li+ and Ag+ are positive in the whole range of compositions, as usual in simple systems. But the effective transport number of either Li+ or Ag+ - depending on the concentration considered - becomes negative if the Hittorf experiments are performed with nitrate electrodes.