Molar excess enthalpies for some systems containing the OH and (or) O groups in the same or in different molecules

2002 ◽  
Vol 80 (3) ◽  
pp. 292-301 ◽  
Author(s):  
Jose Carlos Cobos ◽  
Isaias Garcia de la Fuente ◽  
Juan Antonio Gonzalez
Keyword(s):  
The Self ◽  
Excess Functions ◽  
Excess Enthalpies ◽  
Effective Dipole Moment ◽  
Group Interactions ◽  
Molar Excess ◽  
Dipole Interactions ◽  
Eras Model ◽  
Self Association ◽  
Molar Excess Volumes

In this work, HmE data at 298.15 K for the systems 1-nonanol + n-C12; 1-nonanol + n-C14; 1-hexanol + 3,6,9-trioxaundecane; and 2-(2-butoxyethoxyethanol) + n-C7 are reported. Measurements were carried out with a standard Calvet-type microcalorimeter. Molar excess functions, including enthalpies and entropies, are carefully examined to report on the main features of the studied solutions. Dipole–dipole interactions between ether molecules are, therefore, of great importance in both 1-alkanols + polyoxaalkanes mixtures and between hydroxyether molecules in alkoxy ethanols + n-alkanes systems. In the second case, it has been attributed to the existence of intramolecular H-bonds in alkoxy ethanols as well as to their higher effective-dipole moment in comparison to that of homologous 1-alkanols. DISQUAC is the only model that can be used to accurately represent thermodynamic functions (except molar excess volumes, VmE) of all of the solutions under study. UNIFAC underestimates dipole–dipole interactions in 1-alkanols + polyoxaalkanes and alkoxyethanols + n-alkanes systems. In exchange, the self-association of the alcohol is overestimated in mixtures of 1-nonanol with n-alkanes. Currently, the ERAS model can only be used to examine these solutions. The variation of the VmE with the size of the n-alkanes is well described. Key words: excess functions, OH group, O group, interactions, models.

Thermodynamics of mixtures containing alkoxyethanols: Part XVII — ERAS characterization of alkoxyethanol + alkane systems

2003 ◽  
Vol 81 (4) ◽  
pp. 319-329 ◽  
Author(s):  
Juan Antonio González ◽  
Susana Villa ◽  
Nicolás Riesco ◽  
Isaías García de la Fuente ◽  
José Carlos Cobos
Keyword(s):  
Equilibrium Constants ◽  
Excess Heat Capacity ◽  
Exact Expression ◽  
The Self ◽  
Excess Enthalpies ◽  
Molar Excess ◽  
Dipole Interactions ◽  
Excess Gibbs Energies ◽  
Eras Model ◽  
Self Association

Alkoxyethanol + alkane systems have been examined in the framework of the ERAS model. An exact expression for the molar excess heat capacity at constant pressure, CPE, of solutions formed by a self-associated compound and an inert solvent has been derived. The CPE and the molar excess enthalpies (HE) and excess volumes (VE), as well as the molar enthalpies of vaporization of the pure alkoxyethanols, are represented accurately by ERAS. The calculated curves for HE and VE are skewed towards high mole fractions of the alkane. The experimental curves are more symmetrical. The opposite behaviour is observed for CPE in solutions with 2-ethoxyethanol, 2-propoxyethanol, or 2-butoxyethanol. The differences between the experimental and theoretical values arise because ERAS does not properly take into account the enhanced dipole–dipole interactions due to the formation of intramolecular H-bonds in alkoxyethanols. As in previous applications, ERAS cannot simultaneously represent molar excess Gibbs energies and liquid–liquid equilibria. DISQUAC, a purely physical theory, improves ERAS predictions for HE (except at high temperatures and pressures) and for CPE. Liquid–liquid equilibria are also described more consistently. The self-association of alkoxyethanols via intramolecular H-bonds and the strong dipole–dipole interactions lead to values of the self-association enthalpy and of the adjustable parameter of the physical contribution to HE and VE that are higher than those of the homomorphic 1-alkanols. In contrast, the equilibrium constants are lower. There is good agreement between the partial molar excess enthalpies at 298.15 K and infinite dilution of 2-alkoxyethanol in 2-alkoxyethanol(1) + n-heptane(2) mixtures and the values of the self-association enthalpies. Key words: alkoxyethanol, intermolecular, intramolecular, H-bond, dipole–dipole interactions.

Thermodynamics of binary mixtures of 1,2-dichloroethane with aromatic hydrocarbons

1980 ◽  
Vol 58 (18) ◽  
pp. 1902-1905 ◽  
Author(s):  
Ram K. Nigam ◽  
Prem P. Singh ◽  
Krishan C. Singh ◽  
Mohan Singh ◽  
Ruchi Mishra
Keyword(s):  
Binary Mixtures ◽  
Aromatic Hydrocarbons ◽  
Vapour Pressure ◽  
Excess Volumes ◽  
Equimolar Mixture ◽  
Excess Enthalpies ◽  
Molar Excess ◽  
Experimental Values ◽  
Molar Excess Volumes

Molar excess volumes, VE at 298.15 and 308.15 K, molar excess enthalpies HE at 308.15 K, and total vapour pressure at 298.15 and 308.15 K. have been measured for binary mixtures of 1,2-dichloroethane with aromatic hydrocarbons. The VE and HE data for an equimolar mixture at 308.15 K only have been utilized to predict VE, HE, and TSE values (using Sanchez and Lacombe theory) for these mixtures as a function of temperature and composition. The agreement between the predicted and the corresponding experimental values is good so far as VE and HE data are concerned but the same is not true of the TSE values.

scholarly journals Aromatic fluorocarbon mixtures. II. Carbon tetrachloride+hexafluorobenzene

1973 ◽  
Vol 26 (2) ◽  
pp. 431 ◽  
Author(s):  
S Ruenkrairergsa ◽  
NF Pasco ◽  
DV Fenby
Keyword(s):  
Carbon Tetrachloride ◽  
Solubility Parameter ◽  
Liquid Mixtures ◽  
Excess Volumes ◽  
Equimolar Mixture ◽  
Excess Enthalpies ◽  
Molar Excess ◽  
Carbon Tetra ◽  
Molar Excess Volumes ◽  
Parameter Theory

The molar excess enthalpies and molar excess volumes of carbon tetra- chloride + hexafluorobenzene have been measured at 298.15 K and 308.15 K. The values for the equimolar mixture at 298 15 K are 490 J mol-1 and 0.875 cm3 mol-1 respectively. The results are compared with the values for other liquid mixtures containing a fluorocarbon as one component, and discussed in terms of solubility parameter theory.

Topological investigations of aniline and substituted anilines in binary solutions containing methylene bromide

1993 ◽  
Vol 71 (12) ◽  
pp. 2183-2188 ◽  
Author(s):  
V.K. Sharma ◽  
Prem Paul Singh ◽  
Sanjeev Maken ◽  
B. Singh
Keyword(s):  
Molecular Species ◽  
Molecular Complexes ◽  
Excess Enthalpies ◽  
Substituted Anilines ◽  
Binary Solutions ◽  
Molar Excess ◽  
Ir Studies ◽  
Graph Theoretical Approach ◽  
Molar Excess Volumes ◽  
Theoretical Analyses

Molar excess volumes and molar excess enthalpies for various (i + j) binary methylene bromide (i) + aniline or N-methyl aniline and + N,N-dimethyl aniline (j) mixtures have been determined as a function of composition at 308.15 K. The data have been analysed in terms of the graph-theoretical approach and Sanchez and Lacombe theory. The graph-theoretical analyses of VE data suggest that aniline, N-methyl aniline, and N,N-dimethyl aniline exist as equilibrium mixtures of monomer and dimer and that these mixtures contain 1:1 molecular complexes. The IR studies lend further credence to the nature and extent of interaction along with support for the proposed structure of molecular species in these mixtures.

Thermodynamic properties of ternary mixtures containing nitrobenzene

1997 ◽  
Vol 75 (12) ◽  
pp. 1896-1904 ◽  
Author(s):  
V.K. Sharma ◽  
Khem Chand Kalra ◽  
A. Katoch
Keyword(s):  
Excess Volumes ◽  
Ternary Mixtures ◽  
Specific Interactions ◽  
Excess Enthalpies ◽  
Text Data ◽  
Molar Excess ◽  
Graph Theoretical Approach ◽  
Experimental Values ◽  
Molar Excess Volumes ◽  
Flory’S Theory

Molar excess volumes, [Formula: see text], and molar excess enthalpies, [Formula: see text], of nitrobenzene (i) + benzene (j) + cyclohexane (k), nitrobenzene (i) + benzene (j) + n-hexane (k), and nitrobenzene (i) + benzene (j) + n-heptane (k) ternary mixtures have been determined dilatometrically and calorimetrically as a function of composition at 298.15 K. The data have been analyzed in terms of (i) the graph-theoretical approach and (ii) Flory's Theory. It has been observed that [Formula: see text], data calculated by graph theoretical as well as Flory's approach compare well with their corresponding experimental values. Keywords: molar excess volumes, molar excess enthalpies, specific interactions, molar volume interaction parameter, molar interaction enthalpy parameter.

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