Conductance studies in amide–water mixtures. VI. Nitrates of sodium, potassium, and ammonium in N,N-dimethylformamide–water mixtures at 25 °C

Abstract

Conductance data for the nitrates of sodium, potassium, and ammonium in N,N-dimethylformamide (DMF) – water mixtures (74.39 ≥ D ≥ 36.11) at 25 °C are reported for the concentration range 0.0003–0.06 mol dm−3. Also densities, viscosities, and dielectric constants of the solvent mixture (DMF–water) are reported at the same temperature. The data have been analysed by the Fuoss (1978) equation excluding the term α. The existence of a maximum in the viscosity at a 1:3 mol ratio of DMF and water is attributed to the formation of a solvated complex DMF•3H2O. The Walden products for all the three salts pass through a maximum while the equivalent conductances show a minimum with the change of DMF content in the solvent mixtures. In any given solvent mixture, the limiting equivalent conductances show the trend NaNO3 < KNO3 < NH4NO3. The existence of a maximum in Walden product is attributed to the dehydration of ions due to presence of the cosolvent (DMF). For all the three salts, the association constant was negligible (KA < 10) in all the solvent mixtures studied.