Internal cation mobilities in the molten binary system Li 2CO 3K 2CO 3

Abstract

Internal mobility ratios of two cations in the molten binary system (Li, K)(CO 3) 0.5 have been measured with the Klemm method. From these and available data on the densities and conductivities, the internal mobilities of Li + and K + have been calculated. Except at a region of relatively high concentration of Li 2CO 3, the Chemla effect occurs, that is, the mobility of the large cation K + is greater that of the small one Li +. The internal mobilities of Li + ions are well expressed by b Li = [ A/( V − V 0)] exp (− E/RT), where A, V 0 and E are constants characteristic of the cation and independent of temperature T, V the molar volume of mixtures, and R the gas constant. Negative deviations from this equation at a small V region may be attributed to the free space effect. For b K such a simple equation does not hold over an extended region of concentration, which suggests that the agitation effect and the free space effect would also play a role for the mobility.