Internal Cation Mobilities in the Binary System NaOH ‐ KOH

Abstract

Internal mobility ratios of the two cations in the molten binary system (Na, K)OH have been measured with the Klemm method. From these and available data on the densities and conductivities, the internal mobilities of Na+ and K+ions referred to as and , respectively, have been calculated. With increasing concentration of , increases, whereas decreases. The Chemla effect occurs except at high (mole fraction of ) region. is well expressed by except at a region of small molar volume, where , , and are constants independent of temperature and molar volume of the mixture . Negative deviation of from this relation at high may be attributed mainly to the free space effect resulting from the small free space. The decrease of with an increase of could qualitatively be interpreted on the assumption that the motion of OH− ions becomes less active with partly because of the strong coulombic attraction between Na+ and OH− ions and partly because of the free space effect.