Nikos G. Tsierkezos

Ultrasonic studies of liquid mixtures of either water or dimethylsulfoxide with ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol and 1,4-butylene glycol at 298.15 K

Densities (ρ), speeds of sound (u), and isentropic compressibilities (kS ) of binary liquid mixtures of either water or dimethylsulfoxide (DMSO) with ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TrEG), tetraethylene glycol (TetrEG), 1,2-propylene glycol (PG), and 1,4-butylene glycol (BG) were measured over the entire composition range at 298.15 K. The excess molar volumes (VE ), the deviations in speed of sound (uE ) and the deviations in isentropic compressibility ( ) were determined. The experimental VE , uE and values were fitted to the Redlich–Kister polynomial equation, and the Ak coefficients as well as the standard deviations (d) between the calculated and experimental values were derived. The results provide information concerning the specific interactions between unlike molecules in the binary mixtures.

Conductivities, Partial Molar Volumes, and Isentropic Compressibilities of Sodium, Potassium and Ammonium Thiocyanates in Water +N,N-Dimethylformamide Mixtures at 20°C

Abstract Conductance, ultrasonic velocity, and density measurements are reported for NaSCN, KSCN and NH4SCN in water, N,N-dimethylformamide (DMF), and water + DMF mixtures at 20°C. The limiting molar conductances and association constants have been derived from the Lee–Wheaton conductivity equation. The single-ion conductances have been evaluated using Bu4NBPh4 as the “reference electrolyte”. The limiting molar volumes and apparent isentropic compressibilities have been calculated. The ion–ion and ion–solvent interactions have been discussed.

An investigation on ion association and ion solvation of potassium acetate in alcohol solutions

The molar conductivities (Λ) of potassium acetate in methanol (MeOH), ethanol (EtOH), 1-propanol (PrOH), 2-propanol (isoPrOH), 2-methyl-1-propanol (MPrOH), 1-butanol (BuOH), 1-pentanol (PeOH), and benzyl alcohol (BeOH) were measured at 293.15 K. The concentration dependence of Λ was analysed by means of the Lee–Wheaton conductivity equation in the form proposed by Pethybridge and Taba. From the analysis of the experimental Λ values, the limiting molar conductivities (Λo) and the association equilibrium constants (κ α) were determined. The centre-to-centre distance (a) of the formed ion pairs were assumed to be equal to the Bjerrums distance of closest approach. Furthermore, the ultrasonic velocities (u) and the densities (ρ) were measured in order to determine the limiting partial molar volume (V ϕ o) and the limiting apparent isentropic compressibility ( ). The results provide information regarding the association and solvation of the ions of the investigated electrolyte.

Thermodynamic investigation of the surface tension of liquid mixtures of cis-decaline with either methyl–acetate or n-pentyl–acetate in the temperature range from 283.15 to 303.15 K

Surface tensions (σ) and densities (ρ) of binary liquid mixtures of cis-decaline with either methyl–acetate (MAC) or n-pentyl–acetate (PAC) were measured over the entire composition range at the temperatures 283.15, 288.15, 298.15 and 303.15 K. The excess surface tensions (σE ) and the excess molar volumes (VE ) were calculated. The σE and VE values were fitted by the Redlich–Kister polynomial equation and the Ak coeffients as well as the standard deviations (d) between the calculated and the experimental excess parameters were derived. The σ values were further used for the calculation of the surface entropy (SS ) and the surface enthalpy (HS ) per unit surface area. The lyophobicity (β) and the surface mole fraction ( ) of the surfactant component (either MAC or PAC) were also derived using the extended Langmuir model. The results were used for the characterisation of the molecular interactions at the surface and the bulk-phase region.