VISCOSITY OF SALTY WATER

For over 90 years there has been an unexplained puzzle associated with the viscosity of dilute aqueous salt solutions. More specifically, there is a contribution to the viscosity which is linear in the salt concentration and very ion specific for monovalent salts. This is usually discussed in terms of the Jones-Dole coefficient (B) which is the amplitude of the linear term in the concentration. The A coefficient was derived by Falkenhagen and Onsager many years ago in terms of the Debye-Hückel theory for electrolytes. We shall discuss our current understanding of the Jones-Dole coefficient in the context of ionic hydration.