Ultrasonic Investigations of Molecular Interaction in Binary Mixtures of Cyclohexanone with Isomers of Butanol

Ultrasonic speed, u, and density, ρ, have been measured in binary liquid mixtures of cyclohexanone with the isomers of butanol (n-butanol, sec-butanol, and tert-butanol) at 308.15 K over the entire range of composition. Molar volume (Vm), adiabatic compressibility (ks), intermolecular free length (Lf), acoustic impedance (z), and their excess/deviation along with Δu have been calculated from the experimental data. These values have been fitted to Redlich-Kister type polynomial equation. Positive values of VmE, Δks, LfE and negative values of zE, Δu have been observed for all the liquid mixtures indicating the existence of weak interactions between components. Rupture of H-bond or reduction in H-bond strength of isomers of butanol or breaking of the structure of one or both of the components in a solution causes the existence of dispersions in the present investigated binary mixtures. The data obtained from V-m,1, V-m,2, and excess partial molar volumes V-m, 1E, V-m, 2E, reflects the inferences drawn from VmE. Furthermore, FTIR spectra support the conclusions drawn from excess/deviation properties. The measured values of ultrasonic speed for all the investigated mixtures have been compared with the theoretically estimated values using empirical relations such as, Nomoto, Van Dael and Vangeels, Impedance and Rao specific sound speed.

Thermophysical properties of binary mixtures of N,N-dimethylformamide with three cyclic ethers

Densities and viscosities of the binary mixtures consisting of tetrahydrofuran (THF), 1,3-dioxolane (1,3-DO) and 1,4-dioxane (1,4-DO) with N,N-dimethylformamide (DMF) over the entire range of composition were measured at temperatures 298.15, 308.15 and 318.15 K and at atmospheric pressure. Ultrasonic speeds of sound of these binary mixtures were measured at ambient temperature and atmospheric pressure (T = 298.15 K and P = 1.01?105 Pa). The various experimental data were utilized to derive excess molar volumes (VmE), excess viscosities (?E), and excess isentropic compressibilities (?sE). Using the excess molar volumes (VmE), excess partial molar volumes (and ) and excess partial molar volumes at infinite dilution (and ) of each liquid component in the mixtures were derived and discussed. Excess molar volumes (VmE) as a function of composition at ambient temperature and atmospheric pressure were used further to test the applicability of the Prigogine-Flory-Patterson (PFP) theory to the experimental binaries. The excess properties were found to be either negative or positive depending on the nature of molecular interactions and structural effects of liquid mixtures. Em,1V Em,2VE0,m,1VE0,m,2V.

A thermodynamic study of aqueous acetonitrile: excess chemical potentials, partial molar enthalpies, entropies and volumes, and fluctuations

We measured vapour pressures of aqueous acetonitrile (abbreviated as ACN) at 6, 20, and 37°C, from which excess chemical potentials of ACN (µ EACN) were calculated. We also determined excess partial molar enthalpies of ACN (H EACN) at 6, 20, 30, 37, and 45°C. From these data, excess partial molar entropies of ACN (S EACN) were calculated at 6, 20, and 37°C. Using density data by Benson's group, excess partial molar volumes of ACN (V EACN) were evaluated. The response function data by the same group were also used to evaluate amplitude and wavelength of mean-square fluctuations in terms of volume, entropy, and cross between volume and entropy. All the above quantities and their dependence on the mol fraction of solute, i.e., the effect of additional solute on the above quantities were used to study the effect of acetonitrile on the molecular organization of H2O. It was found that acetonitrile works as a stronger structure-making solute than methanol. Rather its effect on H2O is about the same as that of propan-1-ol.Key words: aqueous acetonitrile, interaction functions, fluctuations.

Some thermodynamic properties of the sulfolane–benzene and sulfolane–dichloromethane systems

Molar excess free energies of the systems sulfolane-benzene and sulfolane–dichloromethane have been calculated from static vapor pressure measurements at 30.00 °C. Refractive indices, excess partial molar volumes of mixing, and enthalpies of mixing at infinite dilution of benzene and dichloromethane were also determined.