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

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.

Limiting equivalent conductances for selected substituted ammonium ions in water

The temperature dependence of the limiting equivalent conductances of the ions 2-methoxyethylammonium, bis-2-methoxyethylammonium, 3-methoxypropylammonium, piperidinium, quinuclidinium, cyclohexylammonium, and diethylammonium have been determined over the range 5–45 °C. The probable effect of these ions on the adjacent water structure has been explored in terms of an approach used by Kay and co-workers and the behaviour in water has been compared with that of other alkylammonium ions.

THE ELECTROLYTIC CONDUCTANCES OF SODIUM CHLORATE AND OF LITHIUM CHLORATE IN WATER AND IN WATER–DIOXANE

The conductances, densities, and viscosities of aqueous solutions of sodium chlorate were determined over the complete range of concentration at 25 °C and at 35 °C. An attempt was made to reproduce the results at 25 °C with the viscosity-corrected Falkenhagen–Leist and Wishaw–Stokes equations. The limiting equivalent conductances of sodium chlorate at 25 °C and 35 °C in water were also determined.The conductances, densities, and viscosities of sodium chlorate at 25 °C and 35 °C were determined in a solvent consisting of 64.5% dioxane, 35.5% water. The limiting equivalent conductances of sodium chlorate at 25 °C and 35 °C and of lithium chlorate at 25 °C in this solvent were determined by analyzing the data with the Fuoss–Onsager equation for associated electrolytes.Finally, conductances of sodium chlorate and lithium chlorate at 25 °C were determined in a solvent consisting of 90% dioxane, 10% water.

CONDUCTANCES AND SURFACE TENSIONS OF AQUEOUS SOLUTIONS OF SODIUM DECANOATE, SODIUM LAURATE, AND SODIUM MYRISTATE, AT 25° AND 35°

The equivalent conductances of aqueous solutions of sodium decanoate, sodium laurate, and sodium myristate have been determined from the very dilute region up to saturation concentration, at 25° and 35°. The limiting conductances have been obtained from the measurements in the usual way. In addition and for the sake of completeness, the limiting equivalent conductances of sodium formate, sodium acetate, sodium propionate, and sodium butyrate have also been determined at 35°, since they were not known at this temperature.The effect of increasing chain length on mobility is discussed. From a consideration of the experimental and the theoretical values of the slopes of the plots of equivalent conductance against the square root of the concentration, it is concluded that some sort of interaction, possibly a reversible dimerization of anions, occurs, even in the dilute region, and this could account for the lower experimental values of the slope. This phenomenon has been observed with other long chain electrolytes, however, and the hypothesis of dimerization is not the only possible one.The critical micelle concentrations have been determined, and recent concepts of micelle formation are applied to interpret their structure. The surface tensions of the aqueous solutions have been measured at 25° and 50°.

THE ELECTRICAL CONDUCTIVITIES OF SOME TETRA-n-ALKYLAMMONIUM SALTS IN ACETONITRILE

The conductances of a number of tetra-n-alkylammonium bromides and iodides have been measured in acetonitrile. Limiting equivalent conductances and dissociation constants have been evaluated by two methods. Limiting equivalent ionic conductances have been evaluated from these results. Correlations have been made of the effect of ion size on the ionic conductances and on the relative order of magnitude of the dissociation constants. In an appendix the limiting ionic conductances of a number of other ions have been collected from the existing literature.

Conductances of electrolytes in solutions of the sucrose polymer Ficoll

The limiting equivalent conductances of several electrolytes have been measured at 25� in aqueous solutions of the synthetic sucrose polymer Ficoll. Though the viscosity of the solutions is several times that of sucrose solutions of the same percentage by weight of solute, the limiting conductances of small ions in them are little different from those in sucrose solutions. It is concluded that the polymer molecules form loose networks to a large extent permeable to small ions.

Solubility of simple aluminium compounds expected in soils. II. Hydrolysis and conductance of Al3+

The results of conductimetric measurements on dilute aluminium chloride solutions at 25� were found to be best fitted by the limiting equivalent conductances A01/3Al3 + = A01/2AlOH2+ = 58.2 with the parameter for ionic diameter 6.0A and by *K1 = log [(AlOH2+)(H+)/(Al3+)] = - 5.05 when it was assumed that AlOH2+ and H+ concentrations produced by hydrolysis were equal in the measured solutions. Potentiometric measurements and calculations from solubility work gave *K1 = -5.00 and -4.97 respectively. After small changes, e.g. by aging, dilute aluminium salt solutions conform to the solubility expression for aluminium hydroxide, log [(AlOH2+) (OH-)2] = -23.31.

CONDUCTANCES OF AQUEOUS SOLUTIONS OF SODIUM OCTANOATE AT 25° AND 35° AND THE LIMITING CONDUCTANCE OF THE OCTANOATE ION

Equivalent conductances, densities, and viscosities of aqueous solutions of sodium octanoate have been determined at 25° and 35 °C, at concentrations ranging from 0.0002 M to 2.8 M. The limiting equivalent conductances of the octanoate ion have been determined as 23.08 mhos and 29.09 mhos, at 25° and 35 °C respectively.Comparison has been made of our experimental conductances with those calculated, using the equations of Robinson–Stokes, of Falkenhagen–Leist, and of Fuoss.No evidence has been found of micelle formation in solutions of sodium octanoate.