MODEL SYSTEM FOR CONCENTRATED ELECTROLYTE-SOLUTIONS - THERMODYNAMIC AND TRANSPORT-PROPERTIES OF ETHYLAMMONIUM NITRATE IN ACETONITRILE AND IN WATER

Ethylammonium nitrate (ETAN), a low melting fused salt which is completely miscile in water and in many non-aqueous solvents, was used as a model system for the study of concentrated non-aqueous electrolyte solutions. Acetonitrile (AN) was chosen as a representative aprotic solvent. Some data were also obtained for wafer as solvent. The properties investigated over the whole mole fraction range, many as a function of temperature, were solid-liquid phase diagram, volume, heat capacity, conductivity and viscosity. Most properties in both solvents vary in a regular fashion over the whole mole fraction range and the properties at high concentration rapidly tend to those of the molten salt. The apparent volumes and heat capacities vary linearly with lnX(2) over a large mole fraction range. There is evidence of significant association in AN (K-A = 1094 l-mol(-1)) but not in water. The low concentration thermodynamic data were fitted with an association model using the above K-A to obtain the partial molar quantities of ETAN at infinite dilution and in the associated state. These latter values are of the same magnitude as the molar quantities of the molten electrolyte.