Diffusion potentials and transport numbers in molten alkali chlorides and their binary mixtures

✍ Scribed by M.V. Smirnov; K.A. Aleksandrov; V.A. Khokhlov

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 714 KB
• Volume: 22
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(77)85118-9

✦ Synopsis

Diffusion potentials at porous asbestos diaphragms separating chloride melts of different cation comnositions have been measured as functions of temperature making use of cells with chlorine electrodes. Between individual molten alkali chlorides the diffusion potentials were found to increase with the difference in their cation radii reaching a maximum of -35 mV for LiCl : CsCl and a minimum of -2 mV for RbCl j CsCl. The melts with smaller alkali cations were moreelectropositive in all cases. From the experimental data for the systems M&l j NMrCI + (1 -N)M,,Cl where M, = Cs or K and M,, = Li or Na, transport numbers of those cations were computed as functions of N. They proved to be smaller for Li' and Na' and larger for Cs' and K' as compared with their additive values. The cation mobilities were calculated. For Cs+ or K' they are a little higher in the salt mixtures than in their individual chlorides whereas for Li+ or Na' they are considerably lower. Such changes in cation transport numbers and mobilities can be explained in terms of autocomplex structure model for molten alkali halides developed recently by M. V. Smimov.