Viscosities and electrical conductances of some tetraalkylammonium and common ions in aqueous binary mixtures of N,N-dimethylacetamide at 298.15K

505-510Precise measurements on electrical conductances in the concentration range 0.022-0.044 mol dm-3 are reported for tetraalkylammonium bromides, R4NBr (R =ethyl to hexyl), sodium bromide (NaBr) and sodium tetraphenyl borate (NaBPh4) in binary mixture of N,N-dimethylacetamide (DMA) and water at 0.5 mole fraction of DMA at 298.15K. Viscosities of these salts except tetrahexylammonium bromide (Hex4NBr) have also been measured in the concentration range 0.008-0.10 mol dm-3 in this aqueous binary mixture at the same temperature. The conductance data have been analysed by the 1978 Fuoss conductance- concentration equation in terms of the limiting molar conductance (Ʌo), the association constant (KA) and the association diameter (R). Viscosity data have been analysed by means of Jones-Dole equation and B-coefficients evaluated. The limiting ionic conductances and the ionic contributions to the viscosity B-coefficients have been estimated from the appropriate division of the limiting molar conductivity and the B-coefficient values using the ‘reference electrolyte’ method. The results have been interpreted considering the selective solvation, size and structure forming effect of ions and also the movement of ions in a strongly hydrogen bonded solvent system formed between water and the peptido dipole in DMA

Micellization behaviour of lithium dodecyl sulphate in aqueous solutions using conductivity, density and adiabatic compressibility measurements

1793-1799Temperature effects on micellar behaviour of lithium dodecyl sulphate in aqueous solutions have been measured using conductometric, densiometric, and interferrometric techniques. All these methods yield almost identical critical micelle concentration (cmc) for the surfactant system. Conductivity studies, in the range 288.15-318.15 K at 5 K intervals, show a shallow minimum of the cmc values at around 298.42 K. The ionization degree of micelles (α), has been round to increase whereas the standard free energy of micellization (ΔGoɩɩɩ) decreases upon increase in temperature. Variation in standard enthalpy upon aggregation has been calculated by using Gibbs-Helmholtz equation. From density measurements carried out at 288.15, 298.15 and 308.15 K. the changes of the apparent molar volume upon micellization of the surfactant have been calculated. The apparent adiabatic compressibilities of the surfactant solutions have also been calculated using density and ultrasound velocity measurements and provide information on the solution behaviour of the surfactant in aqueous solution

A study on the transport behaviour of tetraphenylarsonium, tetraphenylphosphonium and some common ions in propylene carbonate from viscosity and conductance data

25-30Viscosity measurements for solutions of tetraphenylarsonium chloride (Ph4AsCl); tetraphenylphosphonium bromide (Ph4PBr) and sodium tetraphenylborate (NaBPh4.) in propylene carbonate (PC) are reported at 25, 35 and 45°C. Electrical conductances of these salts and that of tetrabutylammonium tetraphenylborate (Bu4NBPh4.) have also been measured at 25°C. Viscosity data have been analysed by means of Jones-Dole equation and B coefficients evaluated. Conductance data have been analysed by 1978 Fuoss conductance equation in terms of equivalent conductance (Λ0), association constant (KA)and association distance (R). Limiting ionic values have been determined using the 'reference electrolytes' Bu4NBBu4 and Bu4NBPh4. Stokes radii have also been evaluated and the study indicates that Na+ and Cl- are substantially solvated while other ions are scarcely solvated and remain as free ions in this medium

Apparent molar volumes and apparent molar adiabatic compressibilities of some symmetricai tetraalkylammonium bromides in 1,2-dimethoxyethane

288-293Apparent molar volumes (фv) and apparent molar adiabatic compressibilities (фK) of four symmetrical tetraalkylammonium bromides have been determined in 1,2-dimethoxyethane from precise density and sound velocity measurements. Limiting apparent molar volumes and adiabatic compressibilities of the salts obtained from the concentration dependence of фv and фK data are separated into ionic contributions. The data have been quantitatively interpreted in terms of solute-solvent and solute-solute interactions. Strong electrostriction occurs around bromide ions whereas the larger tetraalkylammonium ions which are scarcely solvated in 1,2-dimethoxyethane, cause a greater degree of disorder in the solvent structure

A study on volumetric and compressibility properties of some lithium salts in N,N-dimethylacetamide at 25°C

1812-1815Apparent molar volumes (ϕv) and apparent molar adiabatic compressibilities (ϕk) have been determined for solutions of some lithium salts (Li Cl, LiBr, LiI, LiClO4, LiBF4) in N,N-dimethylacetamide at 25°C from density and sound velocity measurements. Limiting apparent molar volumes (ϕv0)of the salts have been obtained from ϕv vs √c curves and separated into ionic contributions. The apparent molar compressibilities at infinite dilution, ϕk0 have been evaluated by filling ϕk against √c by the method of least squares and also the ionic values reported. The results indicate that as the size of the anion increases (cation being the same) electrostatic solvation has an increasing tendency and compressibility of the solution decreases more. The data have been quantitatively explained in terms of solute-solvent interactions along with the degree of disorder in the solvent structure