US EPA

1053897 

Journal Article 

Electric conductivities of 1:1 electrolytes in high-temperature ethanol along the liquid-vapor coexistence curve. I. NaBr, KBr, and CsBr 

Takahata, K; Hoshina, TA; Tsuchihashi, N; Ibuki, K; Ueno, M 

2010 

Yes 

Journal of Chemical Physics
ISSN: 0021-9606
EISSN: 1089-7690 

132 

11 

114501 

English 

20331299 

10.1063/1.3353955 

WOS:000275825500030 

The molar electric conductivities Lambda of NaBr, KBr, and CsBr were measured in liquid ethanol at temperatures from 60 to 220 degrees C along the liquid-vapor coexistence curve. The limiting molar electrolyte conductivities Lambda(o) and the molar association constants K(A) were determined by the analysis of the concentration dependence of Lambda. The friction coefficients zeta for the Na(+), K(+), Cs(+), and Br(-) ions were estimated from Lambda(o) by an assumption that the cationic transference number of KBr is independent of temperature and density. The density dependences of zeta thus obtained together with literature values at higher densities (lower temperatures) were examined. zeta increases with decreasing density at densities above 2.0rho(c), where rho(c)=0.276 g cm(-3) is the critical density. At lower densities, the density dependences of zeta depend on ion. The relative contribution of the nonviscous effect in zeta was estimated by Deltazeta/zeta, where Deltazeta was the difference between zeta and the Stokes friction coefficient. At densities above 2.7rho(c), Deltazeta/zeta slightly decreases with decreasing density except for the Cs(+) ion. At densities below 2.7rho(c), Deltazeta/zeta increases with decreasing density and the density dependence is larger for larger ion. The results at densities above 2.2rho(c) were well explained by the Hubbard-Onsager (HO) dielectric friction theory [J. Hubbard, J. Chem. Phys. 68, 1649 (1978)] based on the sphere-in-continuum model. Below 2.2rho(c), however, experimental Deltazeta/zeta tends to be larger than the prediction of the HO theory. The lower limit density of the validity range of the HO theory is slightly higher in ethanol than in methanol. 

caesium compounds; continuum mechanics; electrolytes; internal friction; ionic conductivity; permittivity; potassium compounds; sodium compounds; viscoelasticity