The Viscosity of Aqueous Solutions of Alkali and Tetraalkylammonium Halides at 25 degrees C

The viscosities of most alkali and tetraalkylammonium halides have been measured in water at 25 degrees C. The relative viscosities can befitted, up to 1 M, with the relation eta(r) = 1 + A(eta)c(1/2) + B(eta)c + D(eta)c(2). The A(eta) term depends on long-range coulombic forces, and B(eta) is a function of the size and hydration of the solute. When combined with partial-molal-volume data, the difference B(eta) - 0.0025 (V) over bar (0) is mostly a measure of the solute-solvent interactions. Ionic B(eta) are obtained if the tetraethylammonium ion is assumed to obey Einstein's law. The D(eta) parameter depends on higher terms of the long-range eoulombic forces, on higher terms of the hydrodynamic effect, and on structural solute-solute interactions. As such, it cannot be interpreted unambiguously.