Romolo Francesconi

Liquid-vapour equilibrium in binary mixtures with associations of the components—II the acetic acid—trichloroethylenen system

Abstract The data for the isobaric equilibrium in the acetic acid—trichloroethylene system were determined using an apparatus in which the liquid and vapour were made to circulate. Analysis of the data for this system, which is characterized by dimerization of the acetic acid in the vapour phase, permits application of the semi-integral consistency criterion formulated in Part I [1]. The results fully confirm the existence of only the dimer of acetic acid in the vapour phase. They also afford a test of the very good consistency of the equilibrium data when transferred from isobaric conditions to isothermal ones. Furthermore, they prove that the terms due to the non-ideal nature of the vapour phase make only a negligible contribution.

Excess molar enthalpies of binary mixtures containing dimethyl carbonate or diethyl carbonate and one of six methyl n-alkyl ketones Application of an extended cell model

Abstract Excess molar enthalpies H E m of binary mixtures containing dimethyl carbonate or diethyl carbonate and six methyl n -alkyl ketones have been determined at 298.15 K and atmospheric pressure using a flow microcalorimeter. The systematic behaviour of H E m , increasing with the increase in the number of the carbon atoms in the ketone, is confirmed for all mixtures with the exception of mixtures of diethyl carbonate and 2-propanone. The experimental data have been correlated by means of the Redlich-Kister equation and results are interpreted in terms of molecular interactions, and are examined by an extended cell model.

Excess enthalpies for binary mixtures of toluene, p-xylene or pseudocumene + methyl-n-alkyl ketones. Application of an extended cell model

Abstract Excess molar enthalpies HE of the fifteen binary mixtures containing toluene, p-xylene or pseudocumene + five methyl-n-alkyl ketones at 298.15 K and atmospheric pressure are reported. The results confirm for p-xylene or pseudocumene + ketones the systematic behavior of HE with respect to the chain length of the ketone, whereas for the toluene + 2-undecanone mixture, an inversion in the tendency of HE has been noted (Patterson effect). The experimental data are examined by an extended cell model.

Excess molar enthalpies of binary mixtures containing dialkylcarbonates + cyclic ketones at 298.15 or 313.15 K

Abstract Excess molar enthalpies H E m for the binary mixtures containing dimethylcarbonate or diethylcarbonate + cyclohexanone, 2-methylcyclohexanone and 2,6-dimethylcyclohexanone have been determined at 298.15 and 313.15 K and at atmospheric pressure, utilizing an isothermal flow microcalorimeter. The experimental values have been correlated by the Redlich-Kister equation and the parameters have been evaluated by least-squares analysis. For all the mixtures, the H E m values are positive with a maximum ranging from + 190 up to 700 J mol −1 . All curves present a regular trend decreasing with an increase in temperature. The experimental data have been examined by an extended cell model.

Liquid—vapour equilibrium in binary mixtures with associations of the components—I General consistency criterion

Abstract A thermodynamic method has been developed to provide a direct semi-integral criterion of the consistency of liquid—vapour equilibrium data under isobaric and isothermal conditions for binary mixtures with associations between the components in the two phases. The method differs from others by the use of the equality between the microscopic and the macroscopic chemical potentials of the species in both phases. This permits the introduction of fugacity and activity coefficients, which are more convenient to use. Furthermore, it does not require any information on the state of the association in the liquid. The semi-integral criterion enables one to examine without any analytical or graphical difficulty the consistency of the data throughout the whole concentration range of the components.

A calorimetric study of propylene carbonate + acetic or propionic acid at (288.15, 298.15 and 313.15) K

Abstract Determinations of heat capacities, Cp, and excess molar enthalpies, HEm, of the binary mixtures propylene carbonate + acetic or propionic acid were carried out at (285.15, 298.15 and 313.15) K using a Perkin-Elmer DSC differential scanning calorimeter and an LKB flow microcalorimeter. All experimental values are positive and increase with the increase of temperature. The data have been fitted to a simple cubic polynomial (for Cp) and the Redlich-Kister equation (for HEm) to estimate the adjustable parameters and standard deviations of these systems. Results have been discussed in terms of molecular interactions and have been interpretated by an extended cell model.

Excess molar enthalpies and excess molar volumes of binary mixtures containing p-xylene + cyclic ethers

Abstract Excess molar enthalpies H E , and excess molar volumes V E , of mixturesof p -xyleae with the cyclic ethers oxolane, oxane, 1,3-dioxolane, and 1,4-dioxane have been determined by means of a flow microcalorimeter and a digital density meter at 298. 15″ K and afinospheric pressure. The experimental values are correlated by polynomiah equations. V E is positive over the entire range of mole fractions for p -xylene-1,4-dioxane, but is negative for the other mixtures. H E is positive for the mixtures involving the diethers-1,3-dioxolane and 1,4-dioxane, and negative for the monoethers. The heat effects are qualitatively discussed in terms of molecular interactions.

Excess enthalpies of binary mixtures containing 1,3-dioxolane and cyclic compounds

Abstract Excess molar enthalpies, HE, of binary mixtures containing 1,3-dioxolane plus toluene, p-xylene, 1,2,4-trimethylbenzene, ethylbenzene, 1,4-dimethylbenzene, 1,4-dimethylcyclohexane and ethylcyclohexane were determined by means of a flow microcalorimeter. Experimental HE values were correlated by the Redlich-Kister polynomial. The aromatic set of compounds shows calorimetric behaviour markedly different from that of corresponding aliphatic cyclic compounds.

Excess molar enthalpies of diethyl carbonate + fourteen n-alkyl alkanoates at 298.15 K

Abstract Excess molar enthalpies of binary mixtures containing diethyl carbonate + fourteen n -alkyl alkanoates (six acetates, four propanoates and four butyrates) have been determined at 298.15 K and at atmospheric pressure using an LKB flow microcalorimeter. The experimental data have been fitted to the Redlich-Kister equation to estimate the binary parameters. The results have been qualitatively discussed.

Stefan flow in binary mixtures of gases

Abstract An attempt has been made to establish whether or not there are variations of pressure and barycentric velocity in a laminar layer composed of a binary gas mixture in contact with a liquid phase from which one of the two components evaporates or condenses while the other is stationary. The combination of the equations of motion, of continuity and of state, with density ϱ and viscosity η not constant, leads us to the conclusion that pressure is uniform throughout the layer while the velocity of the barycentre varies according to the mean molecular weight. The composition profile thus assumes the form given by the classical treatment where both ϱ and η are held constant.