Volumetric and Viscosimetric Measurements for Methanol + CH3–O–(CH2CH2O)n–CH3 (n = 2, 3, 4) Mixtures at (293.15–303.15) K and Atmospheric Pressure: Application of the ERAS Model

Abstract

Densities,  , and kinematic viscosities,  , have been determined at atmospheric pressure and at (293.15-303.15) K for binary mixtures formed by methanol and one linear polyether of the type CH3-O-(CH2CH2O)n-CH3 (n =2,3,4). Measurements on  and  were carried out, respectively, using an Anton Paar DMA 602 vibrating-tube densimeter and an Ubbelohde viscosimeter. The  values are used to compute excess molar volumes, E m V , and, together with  results, dynamic viscosities ( ). Deviations from linear dependence on mole fraction for viscosity,   , are also provided. Different semi-empirical equations have been employed to correlate viscosity data. Particularly, the equations used are: Grunberg-Nissan, Hind, Frenkel, Katti-Chaudhri, McAllister and Heric. Calculations show that better results are obtained from the Hind equation. The E m V values are large and negative and contrast with the positive excess molar enthalpies, E m H , available in the literature, for these systems. This indicates that structural effects are dominant. The   results are positive and correlate well with the difference in volume of the mixture compounds confirming the importance of structural effects. The temperature dependences of  and of the molar volume have been used to calculate enthalpies, entropies and Gibbs energies, * G  , of viscous flow. It is demonstrated that * G  is essentially determined by enthalpic effects. Methanol + CH3-O-(CH2CH2O)n-CH3 mixtures have been treated in the framework of the ERAS model. Results on E m H are acceptable, while the composition dependence of the E m V curves is poorly represented. This has been ascribed to the existence of strong dipolar and structural effects in the present solutions.

Measurement and Correlation of the Solubility and Thermodynamic Properties of Ribavirin(II) in Nine Pure Solvents and (1-Propanol + Water) Binary Solvents

“…Hence, the mixing thermodynamic parameters of the solution can be obtained from the experimental solubility data using the thermodynamic model according to the Lewis–Randall rule. The thermodynamic properties of the ideal mixing process are expressed as follows − where x i is the molar fraction of ribavirin­(II) and solvents, n is the number of solvents, and Δ mix G id , Δ mix S id , and Δ mix H id represent the mixed Gibbs energy, mixture entropy, and mixing enthalpy of the ideal solution, respectively. For an actual solution, the mixing thermodynamic properties can be calculated by the following relation where G E , H E , and S E refer to the excess Gibbs free energy, excess enthalpy, and excess entropy, respectively, and Δ mix G id , Δ mix H id , and Δ mix S id represent the corresponding mixing properties of the ideal solution.…”