Heat capacity of liquids : critical review and recommended values

Thermodynamics of mixtures with strongly negative deviations from Raoult's Law: Part 4. Application of the DISQUAC model to mixtures of 1-alkanols with primary or secondary linear amines. Comparison with Dortmund UNIFAC and ERAS results

A study was carried out in which new experimental data on heat capacities of pure liquid organic and some inorganic compounds were compiled, critically evaluated, and recommended values provided. Compounds included in the compilation have a melting point below 573 K. The bulk of the compiled data covers data published in the primary literature between 1993 and 1999 and some data of 2000. However, some data from older sources were also included. The data were taken from almost 1030 literature references. Parameters of correlating equations for temperature dependence of heat capacities of liquids were developed. This paper is an update of a two volume monograph entitled Heat Capacity of Liquids: Critical Review and Recommended Values (96ZAB/RUZ) that was published in 1996 in the Journal of Physical and Chemical Reference Data as Monograph No. 6 and was the product of the IUPAC Project No. 121/11/87.

Heat Capacity of Liquids: Critical Review and Recommended Values. Supplement II

Thermodynamics of liquid mixtures containing a very strongly polar compound: Part 6. DISQUAC characterization of N,N-dialkylamides

Binary mixtures of alkoxyethanols, CH3–(CH2)n–O–(CH2CH2O)mOH, and n-alkanes or cyclohexane are characterized in terms of DISQUAC. The corresponding dispersive (DIS) and quasichemical (QUAC) interchange coefficients, Ceh,lDIS/QUAC, for the (e,h) contacts (type e, –O–; type h, –OH) are given. In comparison with the values for 1-alkanol + monooxalkane systems, the proximity effects in CH3–(CH2)n–O–CH2–CH2–OH + n-alkane mixtures lead to an increase in the Ceh,lDIS and Ceh,lQUAC (l
= 1,2) coefficients and to a decrease in Ceh,2DIS. For other hydroxyethers (3-methoxypropanol,
4-methoxybutanol), the Ceh,lQUAC (l
= 1,2) coefficients approach those of 1-alkanol + monooxalkane mixtures with increasing separation between the –O– and OH– groups. However, the Ceh,2DIS coefficient is still lower than in alcoholic solutions, indicating that proximity effects in the framework of DISQUAC remain. DISQUAC yields a consistent description of the vapor–liquid equilibria, VLE, and of liquid–liquid equilibria, LLE. Good results are obtained for azeotropic data. The coordinates of the critical points are represented over a reasonable range of composition and temperature. Excess molar enthalpies HmE and the excess molar heat capacity at constant pressure, CpmE, are well reproduced. The typical large deviations for properties at infinite dilution, excess
molar partial enthalpies, HmE,∞, and natural logarithms of activity coefficients, ln γi∞, of the associated compound are found. Thermodynamic properties of alkoxyethanol + alkane mixtures are determined by the self-association of the polar compound ia both inter- and intramolecular H-bonds, as well as by dipole–dipole interactions between alkoxyethanol molecules. These interactions are analyzed in terms of the effective dipole moments () and are more important than in 1-alkanol + alkane mixtures. The dipole–dipole interactions in systems with alkoxyethanols decrease along a homologous series, and are enhanced by the presence of two ether atoms. Intramolecular H-bonds are more relevant than the intermolecular H-bonds and become weakened with the separation between the –O– and –OH groups
of the hydroxyethers.

W. Egger

Papers

Thermodynamics of liquid mixtures consisting of a very polar and a non-polar aromatic: (benzonitrile + benzene, or toluene)