Angelo Dell'Atti

Solute-Solvent interactions in water-rich mixtures. II. Ionic conductances in water-dimethylsulfoxide mixtures at 25°C

Conductances of sodium bromide, iodide, and perchlorate, potassium chloride, and tetraphenylboride (BPh4−) as well as triisoamyl-n-butylammonium iodide (i-Am3BuNI) have been measured in aqueous mixtures containing up to 20 mole percent dimethylsulfoxide (DMSO) at 25°C. Experimental data were analyzed by the 1965 Fuoss-Onsager-Skinner (FOS) equation. Single-ion limiting equivalent conductances were calculated by assuming that λ0 (i−Am3BuN+=λ0 (BPh4−). The variations of the limiting ionic Walden products are discussed on the basis of acid-base type interactions for cations, and on the basis of structural effects for anions.

Excess volumes and viscosity of water—sulfolane mixtures at 30, 40 and 50°C

Abstract Densities and viscosities of water—sulfolane mixtures have been measured at 30, 40 and 50°C over the whole mole fraction range. From density data apparent molar volumes of both components and deviations from ideal volumes of mixing have been evaluated at the three temperatures. From viscosity data activation parameters of viscous flow have been computed. Data obtained seem to confirm that sulfolane acts as a structure-breaker to water even at low concentrations.

Ionic contributions to the viscosity B coefficients of the Jones–Dole equation. Part 5.—Acetonitrile

The B coefficients of the Jones–Dole viscosity equation are a measure of the size of the ions and of the interaction between the ions and the solvent. The B coefficients have been determined for the electrolytes Bu4NBu4B, Bu4NBr, Bu4NI, Ph4PBr, Ph4PI, NaI and NaPh4B, and for the homologous series from Et4NBr to Hept4NBr in acetonitrile at 25 and 35 °C. Ionic B values for the bromide and iodide ions have been calculated from the B coefficients for the tetra-alkylammonium solutions and are compared with those obtained from the tetraphenylphosphonium solutions. The transition-state treatment has been applied to the results, and the thermodynamic activation parameters for viscous flow have been calculated. These are compared with those found previously for solutions of dimethyl sulphoxide, hexamethylphosphoric triamide and N,N-dimethylformamide, and are discussed in terms of the new theory of B coefficients proposed by Feakins.

Excess heat capacities and excess volumes of binary liquid mixtures of chloroform with cyclic ethers at 298.15 K

Abstract Molar excess heat capacities at constant pressure, C E p , of binary liquid mixtures chloroform + oxolane, chloroform + 1,3-dioxolane, chloroform + oxane, and chloroform + 1,4-dioxane have been determined at 298.15 K from measurements of volumetric heat capacities in a Picker flow microcalorimeter. A precision of ±0.04 J K −1 mole − was achieved by using the stepwise procedure. Experimental molar excess heat capacities are compared with values derived from H E results at different temperatures. Excess molar volumes, V E , for the same systems at 298.15 K have been determined by measuring the density of the pure liquids and solutions with a high-precision digital flow densimeter.

Excess volumes of (bromobenzene + an n-alkane) at 298.15 K

Abstract Excess molar volumes V m E at 298.15 K have been determined from density measurements with a high-precision vibrating-tube densimeter for liquid bromobenzene + n -hexane, + n -heptane, + n -nonane, + n -decane, + n -dodecane, + n -tetradecane, and + n -hexadecane. The curves of V m E ( x ) are negative over the whole range of mole fraction x for the mixtures containing n -hexane and n -heptane, sigmoid for those with n -nonane, and become completely positive for the n -alkanes from C 10 to C 16 . The magnitude of V m E and its dependence on the chain-length of the n -alkane are discussed.

Excess heat capacities and excess volumes of binary liquid mixtures of 1,1,1,-trichloroethane with cyclic ethers at 298.15 K

Abstract Measurements of volumetric heat capacities at constant pressure, C p / V ( V being the molar volume), at 298.15 K, of the binary liquid mixtures 1,1,1-trichloroethane + oxolane, +1,3-dioxolane, +oxane, +1,3-dioxane, and +1,4-dioxane were carried out in a Picker-type flow microcalorimeter. Molar heat capacities at constant pressure. C p , and molar excess heat capacities, C E p , were calculated from these results as a function of the mole fraction. C E p values for these systems are positive and the magnitude depends on the size of the cycle and on the relative position of the oxygen atoms in the cyclic diethers. The precision and accuracy for C E p are estimated as better than 2%. Molar excess volumes, V E , for the same systems, at 298.15 K, have been determined from density measurements with a high-precision digital flow densimeter. The experimental results of V E and C E p , are interpreted in terms of molecular interactions.

Ionic B coefficients in water at 30, 40 and 50 °C

Viscosity measurements of aqueous solutions of sodium chloride, sodium bromide, sodium iodide, sodium perchlorate, sodium tetraphenylborate, tetraphenylphosphonium bromide, tetrabutylammonium bromide and tri-isoamylbutylammonium iodide at 30, 40 and 50 °C are reported. By means of a new method for separating the viscosity B coefficients of the Jones–Dole equation based on BBPh–4=BPPh+4, the ionic values B± at 30, 40 and 50 °C were calculated. This new method is compared with other separation methods and the variation of the ionic B coefficients with temperature is discussed.

Thermodynamic and physical properties of carbon tetrachloride + sulfolane mixtures

Abstract The solid + liquid phase diagram, drawn from thermal and dielectric measurements, is presented. It exibits a miscibility gap at 0.08 ≤ χ2 ≤ 0.58, and two eutectics. The occurrence of a (likely 1:1) intermediate compound, which decomposes on melting into two immiscible liquids, is postulated. Mixed crystals are observed in the sulfolane richer region. Deviations of the liquid mixtures from ideality, positive in the case of viscosity and negative in the case of dielectric constants, are evidenced.

Separation of viscosity B coefficients into ionic contributions. Part 4.—Extrapolation methods using tetra-alkylammonium bromides in dimethyl sulphoxide and hexamethylphosphoric triamide

Viscosity B coefficients of the Jones–Dole equation have been determined with a high degree of precision for Pr4NBr, Bu4NBr, Pe4NBr, Hex4NBr and Hept4NBr in dimethyl sulphoxide and hexamethylphosphoric triamide at 25 and 35 °C. The B coefficients were plotted as functions of the van der Waals volumes, Stokes radii and formula weights of the cations, and the linear portions of the graphs were extrapolated to the zero value of each property tested. The intercepts thus obtained are discussed and compared with the ionic B(Br–) values reported previously using Bu4NBu4B and Ph4PPh4B as reference salts. The reference-salt method is considered to give the best division into ionic contributions.

Ion–solvent interactions in water-rich binary mixtures. Part 2.—Viscometric behaviour of NaCl, NaBr, KCl, KBr and Bu4NBr in water + hexamethylphosphoric triamide mixtures at 25 and 35 °C

The relative viscosities of NaCl, NaBr, KCl, KBr and Bu4NBr have been measured at 25 and 35 °C in water + hexamethylphosphoric triamide mixtures at low percentages of organic cosolvent. Discussion of the B-coefficients of the Jones–Dole equation and of their dependence on temperature in the binary mixtures allows us to highlight changes in the water structure as the percentage of organic cosolvent is increased.