EFFECT OF INTERNAL COULOMB FIELD UPON VISCOSITY OF A FUSED SALT

An experimental determination is made of the effect of the internal Coulomb field in a fused salt upon the viscosity of the fluid. Two fluids of isoelectronic molecules are compared: the salt tetrabutylammonium tetrabutylboride and the nonelectrolyte 5,5-dibutylnonane. The molecules of these fluids are identical except for the charge on the nucleus of the central atom and their coefficients of viscosity are compared at the same temperature and particle number density between 120° and 180°C. The salt viscosity varies from 10 times that of the nonelectrolyte to less than 5 times as the temperature and volume increase. The Brownian model of Kirkwood and Rice yields a ratio of 2 for a similar model system and suggests that the deviation of this ratio from unity is not necessarily caused by the dissipation arising directly from the Coulomb field. Rather it is caused by the repulsive forces which are more effective in the salt because of the shorter intermolecular distances demanded by the Coulomb field of the salt at any given density. © 1968, American Institute of Physics. All rights reserved.