Excess enthalpies of ten binary mixtures of each of methyl methylthiomethyl sulfoxide (MMTSO) and dimethyl sulfoxide (DMSO) with one of the cycloethers (oxane, 1,3- and 1,4-dioxanes, oxolane and 1,3-dioxolane) have been determined at 298.15 K. All the mixtures show positive excess enthalpies over the whole composition range. Excess enthalpies of the cycloether + MMTSO or DMSO decrease with increasing number of oxygen atoms in the cycloether molecules, except for oxolane + MMTSO. Excess enthalpies of MMTSO + cycloethers are smaller than those of DMSO + cycloethers for the same cycloether except for the 1,3-dioxolane mixtures.
Authors:T. Kimura, T. Ozaki, Y. Nakai, K. Takeda, and S. Takagi
The molar excess enthalpies of 1,2- and 1,3-propanediamine+1,2- and 1,3-propanediol have been determined at 298.15 K by using
a twin-microcalorimeter which requires each component liquid 1 to 1.5 cm3 for a series of runs over the whole range of mole fraction. All excess enthalpies are exothermic and large. An equilibrium
constant K1 expressed in terms of mole fractions and standard enthalpy of formation of 1:1 complex have been evaluated by ideal mixtures
of momomeric molecules and their associated complexes.
Excess enthalpies and excess isobaric heat capacities of binary mixtures consisting of acetonitrile, dimethylformamide and benzene were measured at 298.15 K. Excess enthalpy of acetonitrile + benzene is positive and that of acetonitrile + dimethylformamide is negative. That of dimethylformamide + benzene is positive and nearly equals to zero as shown in the previous report . Excess heat capacities of acetonitrile + benzene and benzene + dimethylformamide change sign from negative to positive with increase of benzene. That of acetonitrile + dimethylformamide is not simple. It is slightly positive near both ends of mole fraction and not so large negative in the middle of mole fraction. The curve tends to flatten in that region.
-tolunitrile ( A 9 ) and p -fluorobenzonitrile ( F 8 ) are solid at 298.15 K, the excessenthalpies change for ( o + p ) and ( m + p )- A 9 / F 8 cannot be measured directly by mixing the two pure liquids. For this reason, liquid solutions of binary
The excess molar enthalpies HE of binary mixtures of formamide with N-methylformamide, N-ethylformamide, N-methylacetamide, N-ethylacetamide and N-methylpropion-amide
have been measured as functions of the mole fraction at 308.15 K, using an isoperibol rotating calorimeter. The experimental
values of HE are negative for all mixtures over the whole composition range. Intermolecular interactions in these mixtures are discussed
through comparison of the results with those for corresponding binary mixtures of water.
Authors:B. Marongiu, Alessandra Piras, Silvia Porcedda, and Enrica Tuveri
A flow microcalorimeter has been used to determine excess enthalpies, HE, at 298.15 K for binary mixtures of chloroalkylbenzenes (1)+n-heptane or cyclohexane (2). All systems are characterized by positive values of HEs. These data along with the data available in the literature on HE, molar excess Gibbs energies, GE, and liquid-vapour equilibria (LVE) are treated in the framework of DISQUAC. Using a set of adjusted contact interchange
energies parameters, structure dependent, the model provides a fairly consistent description of the thermodynamic properties
as a function of concentration. The occurrence of the ‘hetero-proximity effect’ between C6H5-and-Cl groups is suggested by the variation of the interchange parameters.
Authors:H. Wilczura-Wachnik, T. Pawłowski, and M. Maciejewska
The experimental data of excess enthalpies for β-carotene/n-alkane+n-alkane/AOT/water
systems at 298.15 K are reported. The HE
dependence on AOT (sodium bis(2-ethylhexyl)
sulfosuccinate) concentration and hydrocarbon chain length was investigated.
The excess enthalpy was measured using the flow microcalorimeter UNIPAN type