Dilip K. Hazra

Conductance of Selected Alkali Metal Salts in Aqueous Binary Mixtures of 2-Methoxyethanol at 25°C

Precise conductance measurements have been performed for lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, sodium perchlorate, and sodium tetraphenylborate in 2-methoxyethanol–water mixtures at four different mole fractions, i.e., 0.056, 0.136, 0.262, and 0.486 of 2-methoxyethanol (69.73 ≥ D ≥26.55) at 25°C in the concentration range 0.0004–0.0642 mol-dm−3. The limiting molar conductivity Λ°, the association constant KA, and the association distance R for the solvent mixtures have been evaluated from the conductance concentration data using the 1978 Fuoss conductance equation. The single-ion conductances have been estimated using the “reference electrolyte” tetrabutylam-monium tetraphynylborate(Bu4NBPh4). The analysis of the data indicates that for most salts ion association is appreciable in the solvent mixtures with a mole fraction of the cosolvent of 0.262 or higher. The results have been interpreted in terms of ion-solvent interactions and structural changes in the mixed solvent media.

Conductance of Some 1:1 Electrolytes in N,N-Dimethylacetamide at 25°C

Precise conductance measurements of solutions of lithium chloride, lithium bromide, lithium iodide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, tetrabutylammonium bromide, and tetrabutylammonium tetraphenylborate in N,N-dimethylacetamide are reported at 25°C in the concentration range 0.005–0.015 mol-dm−3. The conductance data have been analyzed by the 1978 Fuoss conductance equation in terms of the limiting molar conductance (Λ0), the association constant (Ka), and the association diameter (R). The limiting ionic conductances have been estimated from an appropriate division of the limiting molar conductivity of the “reference electrolyte” Bu4NBPh4. Slight ionic association was found for all these salts in this solvent medium. The results further indicate significant solvation of Li+ion, while the other ions are found to be unsolvated in N,N-dimethylacetamide.

Electrical Conductance of Some Symmetrical Tetraalkylammonium and Alkali Salts in N,N-Dimethylacetamide at 25°C

Precise measurements of electrical conductances of solutions of tetraethylammonium bromide, tetrapropylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, tetraheptylammonium bromide, tetraocytylammonium bromide, sodium tetraphenylborate, and potassium tetraphenylborate in N′,N-dimethylacetamide at 25°C are reported for the concentration range 0.005-0.015 mol-dm−3. The conductance data have been analyzed by the 1978 Fuoss conductance-concentration equation in terms of the limiting molar conductance, the association constant, and the association diameter. The limiting ionic conductances have been estimated from the appropriate division of the limiting molar conductivity value of the “reference electrolyte” Bu4NBPh4. Slight ionic association was found for all these salts in this solvent medium. Tetraalkylammonium ions are found to be unsolvated in N,N-dimethylacetamide, whereas significant solvation has been noticed for sodium and potassium ions.

Electrical conductances for some tetraalkylammonium bromides, lithium tetrafluoroborate and tetrabutylammonium tetrabutylborate in propylene carbonate at 25 °C

Conductance measurements are reported for several symmetrical tetraalkylammonium bromides, lithium tetrafluoroborate (LiBF4) and tetrabutylammonium tetrabutylborate (Bu4NBBu4) in propylene carbonate (PC) at 25 °C. The data have been analysed by the 1978 Fuoss conductance equation in terms of the limiting molar conductivity, Λo, the association constant, KA, and the association distance R. The single-ion conductances have been determined from the Λo value of Bu4NBBu4 using it as a ‘reference electrolyte’. The results indicate that with the exception of LiBF4 to some extent, other salts are almost unassociated in this solvent medium. The evaluation of Stokes radii of the ions indicate that Li+ is extensively solvated while the other ions remain almost unsolvated. The results have been discussed in terms of the ion-solvating ability of PC and also compared with the previous values in this system.

Electrical conductances of some alkali-metal salts in N, N-dimethylacetamide-water mixture at 25°C

Abstract Precise measurements on electrical conductances of the solutions of lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), sodium bromide (NaBr), sodium tetraphenylborate (NaBPh4), potassium bromide (KBr), rubidium bromide (RbBr), cesium bromide (CsBr) and tetrabutylammonium bromide (Bu4NBr) in N,N-dimethylacetamide + water (50 v/v) mixture have been reported at 25 °C in the concentration range 0.02–0.05 mol dm−3. The conductance data have been analyzed by the 1978 Fuoss conductance–concentration equation in terms of the limiting molar conductance (Λ0), the association constant (KA) and the association diameter (R). The limiting ionic conductances (λ0±) have been estimated from the appropriate division of the limiting molar conductivity value of the “reference electrolyte” tetrabutylammonium tetraphenylborate (Bu4NBPh4). The electrolytes investigated here are found to be significantly dissociated in this solvent medium and all ions remain unsolvated in N,N-dimethylacetamide + water (50 v/v) mixed solvent system with exception of the lithium ion where significant solvation has been noticed. The results have been interpreted in terms of the specific constitutional and structural factors of the solvent and of the solute ions.

Viscosities of Some Tetraalkylammonium and Alkali-Metal Salts in N, N-Dimethylacetamide at 25 - C

The viscosities of solutions of tetrapropylammonium bromide (Pr4NBr), tetrabutylammonium bromide (Bu4NBr), tetrapentylammonium bromide (Pen4NBr), tetrahexylammonium bromide (Hex4NBr), tetraheptylammonium bromide (Hep4NBr), tetraoctylammonium bromide (Oct4NBr), tetrabutylammonium tetraphenylborate (Bu4NBPh4), sodium tetraphenylborate (NaBPh4), and potassium tetraphenylborate (KBPh4) in N,N-dimethylacetamide are reported at 25°C. The viscosity data havebeen analyzed by the Jones-Dole equation for associated electrolytes to evaluate the viscosity B coefficients of the electrolytes. These data have also been analyzed by the transition-state theory to obtain the contribution of the solutes to the free energy of activation for viscous flow of the solution. The ionic contribution to the viscosity B coefficient and the free energy of activation for viscous flow have been estimated using of the “reference electrolyte” Bu4NBPh4. The bromide, tetraphenylborate, and tetraalkylammonium ions are found to be weakly solvated in N,N-dimethylacetamide, whereas significant solvation has been detected for sodium and potassium ions. The viscosity of the solvent is greatly modified by the presence of all the ions investigated here with the exception of the bromide ion.

Ultrasonic Velocities and Isentropic Compressibilities of Electrolytes in 2-Methoxyethanol from 15 to 35°C

The ultrasonic velocities of lithium tetrafluoroborate (LiBF4), sodium tetrafluoroborate (NaBF4), tetraphenylphosphonium chloride (Ph4PCl), tetraphenylphosphonium bromide (Ph4PBr), and tetraphenylarsonium chloride (Ph4AsCl) in 2-methoxyethanol (ME) have been measured at 15, 25, and 35°C. Apparent molar isentropic compressibilities κφ of these electrolytes were derived from these data supplemented with their densities. Infinite dilution partial molar compressibilities κφo were obtained by extrapolation from the plot of κφ vs. the square root of the molarity. The κφo values of the electrolytes were split into approximate limiting ionic compressibilities κφ±o on the basis of the assumption that κφo (BF−4) = 0. The results have been interpreted in terms of specific constitutional and structural factors of the solvent molecules and of solute ions.

Viscosity B coefficients of some tetraalkylammonium bromides, lithium tetrafluoroborate and tetrabutylammonium tetraphenyl borate in propylene carbonate

Abstract The viscosities of solutions of tetraalkylammonium bromides, R4NBr (R = -C2H5 to -C7H15), lithium tetrafluoroborate (LiBF4) and tetrabutylammonium tetraphenylborate (Bu4NBPh4) in propylene carbonate (PC) have been measured at 25, 35 and 45 °C. The relative viscosities have been analyzed using the Jones-Dole equation in the form of unassociated electrolytes, and the viscosity B-coefficients have been evaluated. The thermodynamic parameters have been calculated using the transition-state treatment and the measured temperature dependencies. Ionic B values have also been derived and discussed in terms of Einsteins equation. The analysis shows that Li+ is highly solvated compared to other cations and anions in this medium.