Excess Enthalpies Of Binary Mixtures Research Articles

Excess enthalpies of binary mixtures containing cyclohexanone

Molar excess enthalpies H E m of (cyclohexanone + benzene or toluene or ethylbenzene or 1-methylethylbenzene or xylene or 1-methylpropylbenzene or butylbenzene or chlorobenzene or bromobenzene or pentane or hexane or heptane or cyclopentane or methylcyclohexane have been measured at T = 298.15 K. In addition, the H E m of six of those mixtures have been measured at T = 303.15 K. The experimental results are discussed in terms of specific molecular interactions.

Excess enthalpies of binary mixtures of cycloheptane or cyclooctane with benzene or toluene or ethylbenzene at 298.15 K

A flow microcalorimeter of the Picker design was used to measure excess molar enthalpies H E at 298.15 K, as a function of the mole fraction x 1, of the binary liquid mixtures cycloheptane (c-C 7H 14) + benzene (c 6h 6) or toluene ( C 6 H 5CH 3) or ethylbenzene (C 6H 5C 2H 5), and cyclooctane (c-C 8H 16) + benzene or toluene or ethylbenzene. The calorimeter was equipped with separators and operated in the discontinuous mode. In each series, H E is largest for the mixture with benzene, and smallest for the mixture with ethylbenzene. For instance at x 1 = 0.5, H E/Jmol −1 is 821 for c-C 7H 14 + C 6H 6 624 for c-C 7H 14 + C 6,H 5CH 3, and 548 for c-C 7H 14 + C 6H 5C 2H 5. For any given aromatic component, H E of the mixture with cycloheptane is slightly larger than H E of the corresponding mixture with cyclooctane. The results are discussed in terms of the simplest version of the KGB theory.

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

Excess molar enthalpies H E 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 H E with respect to the chain length of the ketone, whereas for the toluene + 2-undecanone mixture, an inversion in the tendency of H E has been noted (Patterson effect). The experimental data are examined by an extended cell model.

Excess enthalpies of binary mixtures of 2-, 3-, 4-picoline+n-alkane (C6H14-C10H22) at 298.15 K. Comparison with theory

The molar excess enthalpies measured for binary mixtures of 2-, 3-, 4-picoline +n-alkane (C6H14-C10H22) at 298.15 K have been compared with the Prigogine-Flory-Patterson theory and the Extended Real Associated Solution model estimations.

A method for predicting VLE and HE of chain-like isomers using a modified UNIFAC model

Abstract Chen, J., Li, Z.-C. and Li, Y.-G., 1992. A method for predicting VLE and HE of chain-like isomers using a modified UNIFAC model. Fluid Phase Equilibria, 74: 47-65. Conformation and steric hindrance of chain-like molecules are considered to distinguish the thermodynamic properties of isomers. A method is proposed to adjust the group surface parameters used in a modified UNIFAC group contribution model. By using this method, vapor-liquid equilibria and excess enthalpies of binary mixtures of n-alkanones, n-monoethers or n-alkanoates with n-alkanes are predicted. The prediction accuracy is obviously improved for excess enthalpies and only slightly improved for vapor-liquid equilibria. Results prove that this method is useful for the application of group contribution models to isomers.

Excess enthalpies of binary mixtures containing α,ω-dibromoalkanes. Measurement and analysis in terms of group contributions (disquac)

Arial, M., Muñoz, Embid J., Otín, S., Velasco, I. and Kehiaian, H.V., 1991. Excess enthalpies of binary mixtures containing α,ω-dibromoalkanes. Measurement and analysis in terms of group contributions (DISQUAC).

Excess enthalpies for binary mixtures formed by 2,5,8,11-tetraoxadodecane with homologous n-alkanes

Excess enthalpies, measured at 298.15 K, are reported for binary mixtures of 2,5,8,11-tetraoxadodecane with some homologous n-alkanes from C 7 to C 12. The excess enthalpies are positive with maximum values between 1.7 and 2.3 kJ mol −1, located near the equimolar concentration. Use of the Flory theory to correlate the data is examined.

Excess enthalpies of binary mixtures containing either methylcyclopentane or methylcyclohexane

A flow microcalorimeter of the Picker design was used to measure excess molar enthalpies H E at 298.15 K, as a function of mole fraction, of the mixtures methylcycdopentane (c-C 5H 9CH 3) + cyclopentane (c-C 5H 10), and + methylcyclohexane (c-C 6H 11CH 3), and of methylcyclohexane + n-heptane (n-C 7H 16), + n-decane (n-C 10H 22), + cyclopentane, + benzene (C 6H 6), and + tetrachloromethane (CCl 4). Tne calorimeter was equipped with separators and operated in the discontinuous mode. The H Es of the first-named three systems are negative, those of the remaining four are an positive. At equimolar composition, H E(x 1 = 0.5)/J.mol −1 ranges from −113 for (c-C 5H 9CH 3 + c-C 5H 10) to + 792 for (c-C 6H 11CH 3 + C 6H 6).

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

Excess molar enthalpies, H E, 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 H E 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 Enthalpies of Binary Mixtures of some Hydrocarbons

Excess Enthalpies of Binary Mixtures of some Hydrocarbons

Excess enthalpies of seven binary liquid systems

A Martin-type isothermal displacement calorimeter was constructed for the determination of excess enthalpies of binary mixtures. Seven binary liquid systems of cyclohexane + benzene, + n-hexane, ethanol + benzene, n-butanol + methyl acetate, + ethyl acetate, + n-propyl acetate and + n-butyl acetate were investigated.

Thermodynamische Betrachtungen von Schmelzdiagrammen einiger Systeme aus Methylchlorsilanen und Lutidinen

Abstract A thermodynamic interpretation of the liquidus curves of some methyltrichloro-respectively dimethyldichlorosilane/lutidine-systems is given. Based on certain approximations it was possible to fit thermodynamic functions to the experimental results to obtain the excess datas of binary systems. A comparison between the models of Redlich-Kister, Wilson and the NRTL-formalism for the free excess enthalpy of binary mixtures is given.

Thermodynamics of liquid mixtures containing methyl methylthiomethyl sulfoxide: VII. Excess enthalpies of binary mixtures between methyl methylthiomethyl sulfoxide and each of toluene, o-, m-, p-xylenes and 1,3,5-trimethylbenzene at 298.15 K

Excess enthalpies of five mixtures between methyl methylthiomethyl sulfoxide (MMTSO) and five methylbenzenes, i.e., toluene, o-xylene, m-xylene, p-xylene or 1,3,5-trimethylbenzene, have been determined at 298.15 K. All the mixtures show the positive enthalpy changes over the whole range of mole fractions. Excess enthalpies of MMTSO + methylbenzenes are smaller than that of corresponding dimethyl sulfoxide(DMSO) + methylbenzenes and are increased with the increase of the number of methyl groups in the methylbenzenes. Linear relationships are obtained between the number of methyl groups of methylbenzenes and the excess partial molar enthalpies of MMTSO and benzene, toluene, m-xylene and 1,3,5-trimethylbenzene at infinite dilution.

Excess enthalpies of binary mixtures of acetophenone with benzene and substituted benzenes

Excess molar enthalpies of binary mixtures of acetophenone with benzene, toluene, o-xylene, m-xylene, p-xylene, chlorobenzene, bromobenzene and nitrobenzene have been measured at 298.15 K over the entire range of composition with a solution calorimeter. The excess enthalpies are positive in all the systems over the entire mole fraction range. Comments on the effect of intramolecular interactions on intermolecular interactions are made on the basis of the results.

Excess heat of mixing of binary mixtures of pyridine withn-alkanes at 313.15 K

The molar excess enthalpies of binary mixtures of pyridine with C6–C9n-alkanes have been measured at 313.15 K in the entire composition range. The measuredHE values were compared with those calculated by means of the Prigogine-Flory-Patterson theory and by the ERAS method.

Excess enthalpies of binary mixtures of methyl acetate with methanol, butan-1-ol, hexan-1-ol, and decan-1-ol

Molar excess enthalpies H E of methyl acetate + methanol, + butan-1-ol, + hexan-1-ol, + decan-1-ol have been measured as a function of the liquid composition at 298 K using an isothermal flow calorimeter. H E is positive in all cases ranging from 1000 J mol (methanol) to 2400 J mol (decan-1-ol) in the maximum of the H E curve. Application of a theoretical model which accounts for hydrogen bonding effects as well as for non polar physical interactions indicates that the physical contribution to H E is unusually large compared to the chemical contribution due to hydrogen bonding effects.

Excess enthalpies of binary mixtures of benzene with n-propylbenzene, n-butylbenzene, n-hexylbenzene AT 298.15, 308.15 and 318.15 K

Excess enthalpies of binary mixtures of benzene with n-propylbenzene, or n-butylbenzene, or n-hexylbenzene have been measured at 298.15 K, 308.15 and 318.15 K using an isothermal flow microcalorimeter. The experimental results have been compared with available literature values.

Excess enthalpies of binary mixtures of di-n-pentyl ether with n-alkanes at 298.15 K

Calorimetric measurements of excess enthalpies at 298.15 K are reported for binary mixtures of di-n-pentyl ether with n-hexane, n-heptane, n-octane, n-decane, n-dodecane and n-hexadecane. A correlation of the excess enthalpies of di-n-alkyl ether + n-alkane mixtures in terms of the Flory theory is described for ethers, (C P H 2 p+1 ) 2O with 2 ⩽ p ⩽ 5, and alkanes, C n H 2 n+2 with 6 ⩽ n ⩽ 16. The treatment uses an interchange energy parameter X 12 which is a function of the fraction of oxygen contact surface on the ether molecule, and the fraction of methyl contact surface on the alkane molecule.

Enthalpic second virial coefficients and enthalpies of solution of alkanols as solutes in alkanols as solvents

The method presented previously, for calculating enthalpic second virial coefficients B 2 h from literature data on excess enthalpies of binary mixtures, is applied to alkan-1-ol/ alkan-1-ol (C 1 - C 10) mixtures. By this means 54 B 2 h values and enthalpies of solution at infinite dilution have been obtained for alkan-1-ols as solutes in other alkan-1-ols as solvents. The results for B 2 h are compared with previous results for alkanes as solutes in the same solvents. Using an empirical equation, it is possible to correlate all 54 B 2 h values for the alkan-1-ols as solutes by means of one adjustable parameter.

Studies on thermodynamic properties of binary systems containing alcohols. VII. Temperature dependence of excess enthalpies for n-propanol + benzene an

Excess enthalpies for binary mixtures of n-propanol with benzene and n-butanol with benzene have been determined at eight temperatures from 288.15 to 323.15 K. It is concluded that excess enthalpies for the latter mixture are larger than for the former at the same temperature; maximal values of these two series shift slightly in the alkanol-rich direction with increasing temperature. Approximately linear relations are found between the excess enthalpies and temperature.