Excess molar enthalpies of binary mixtures containing ethylene glycols or poly(ethylene glycols) + ethyl alcohol at 308.15 K and atmospheric pressure

Excess molar enthalpies, , of binary mixtures containing ethylene glycols and poly(glycols) + ethyl alcohol were measured by a flow microcalorimeter at 308.15 K and at atmospheric pressure over the whole composition range. Binary mixtures contain ethyl alcohol + ethylene glycol, + di(ethylene glycol), + tri(ethylene glycol), + tetra(ethylene glycol), + poly(ethylene glycol)-200, + poly(ethylene glycol)-300, + poly(ethylene glycol)-400, + poly(ethylene glycol)-600. Effects of the molecular weight distribution (MWD), of the polymer were investigated too, by preparing three additional samples of poly(ethylene glycol) with the same number average molecular weight (M_n ≈ 300), but different MWD. For all mixtures, results were fitted to the Redlich–Kister polynomial. curves are asymmetrical, showing positive values which vary from 280 J mol⁻¹ (diethylene glycol + ethyl alcohol) to 1034 J mol⁻¹ (mixture containing PEGs (200 + 400) + ethyl alcohol). Effects of changes in the glycols chain length and in MWD on the molecular interactions among the mixture components are discussed.     

Excess molar enthalpies of binary mixtures containing dimethylcarbonate, diethylcarbonate or propylene carbonate + three chloroalkenes at 298.15 K

Excess molar enthalpies H^E_m of dimethylcarbonate, diethylcarbonate or propylene carbonate + trans-1,2-dichloroethylene, + trichloroethylene, and + tetrachloroethylene, respectively have been determined at 298.15 K using an LKB flow-microcalorimeter. Experimental data have been correlated by means of the Redlich-Kister equation and adjustable parameters have been evaluated by least-squares analysis. The H^E_m values range from a minimum value of − 1000 J mol⁻¹ for diethylcarbonate + trans-1,2-dichloroethylene up to a maximum of 920 J mol⁻¹ for dimethylcarbonate + tetrachloroethylene. For each series of mixtures, a systematic increase in H^E_m with an increase in the number of Cl atoms in the chloroalkene molecule has been noted. The results are discussed in terms of the molecular interactions.     

Excess molar volumes of (a cycloalkane + a methylcycloalkane)

Using a vibrating-tube densimeter, excess molar volumes V^E have been obtained at 293.15 and 313.15 K for methylcyclopentane +, methylcyclohexane + cycloheptane, and + cyclooctane.     

Excess molar enthalpies of (methanol + 1-propanol) + oxane or 1,4-dioxane mixtures at the temperature 298.15 K

Experimental excess molar enthalpies H_m^E at the temperature 298.15 K and atmospheric pressure in a flow microcalorimeter are reported for the ternary mixtures: {x₁CH₃OH+x₂C₂H₅OH+(1−x₁−x₂)C₅H₁₀O} and {x₁CH₃OH+x₂C₂H₅OH+(1−x₁−x₂)C₄H₈O₂}. The results have been correlated by means of a polynomial equation and used to construct constant excess enthalpy contours. Further, the results have been compared with those calculated from a UNIQUAC associated-solution model taking into consideration the molecular association of like alcohols, solvation between unlike alcohols and alcohols with oxane (tetrahydropyran) or 1,4-dioxane using only binary information.     

Excess molar enthalpies of the ternary mixtures: (diisopropyl ether or 2-methyltetrahydrofuran) + cyclohexane + n-heptane at 298.15 K

Microcalorimetric measurements of excess molar enthalpies, at 298.15 K, are reported for the two ternary systems formed by mixing either diisopropyl ether or 2-methyltetrahydrofuran with binary mixtures of cyclohexane and n-heptane. Smooth representations of the results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann and Fried model, using only the physical properties of the components and their binary mixtures.     

Excess molar volumes of binary mixtures (an ionic liquid + water): A review

This review covers recent developments in the area of excess molar volumes for mixtures of {ILs (1) + H₂O (2)} where ILs refers to ionic liquids involving cations: imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium and ammonium groups; and anions: tetraborate, triflate, hydrogensulphate, methylsulphate, ethylsulphate, thiocyanate, dicyanamide, octanate, acetate, nitrate, chloride, bromide, and iodine. The excess molar volumes of aqueous ILs were found to cover a wide range of values for the different ILs (ranging from −1.7 cm³ · mol⁻¹ to 1.2 cm³ · mol⁻¹). The excess molar volumes increased with increasing temperature for all systems studied in this review. The magnitude and in some cases the sign of the excess molar volumes for all the aqueous ILs mixtures, apart from the ammonium ILs, were very dependent on temperature. This was particularly important in the dilute IL concentration region. It was found that the sign and magnitude of the excess molar volumes of aqueous ILs (for ILs with hydrophobic cations), was more dependent on the nature of the anion than on the cation.     

DISQUAC predictions of phase equilibria,molar and standard partial molar excess quantities for 1-alkanol+cyclohexane mixtures

Literature data for phase equilibria: vapor-liquid VLE, liquid-liquid LLE, and solid-liquid SLE; molar excess Gibbs energies G ^E , molar excess enthalpies H ^E ; activity coefficients _i and partial molar excess enthalpies H _i ^E,o at infinite dilution for 1-alkanol (1)+cyclohexane (2) mixtures are examined by the DISQUAC group contribution model. For a more sensitive test of DISQUAC, the azeotropes, obtained from the reduction of the original isothermal VLE data, are also examined for systems characterized by hydroxyl, alkane and cyclohexane groups. The alkane/cyclohexane and alkane/hydroxyl interaction parameters have been estimated previously. The cyclohexane/hydroxyl interaction parameters are reported in this work. The first dispersive parameters increase regularly with the size of the alkanol; from 1-octadecanol they are constant; an opposite behavior is encountered for the third dispersive parameters, which are constant from 1-dodecanol. The second dispersive parameters decrease as far as 1-propanol and then increase regularly; from 1-octadecanol they are constant. The quasichemical parameters are equal to those for the alkane/hydroxyl interactions. Phase equilibria, the molar excess functions, and activity coefficients at infinite dilution are reasonably well reproduced. Poor results are found for H _i ^E,o and DISQUAC predictions for H _i ^E,o are strongly dependent on temperature.     

Excess molar volumes of (ethyl formate or ethyl acetate + an isomer of hexanol) at 298.15 K

Excess molar volumes V_m^E were determined over the entire composition range at 298.15 K for ethyl formate or ethyl acetate + hexan-1-ol, +2-methylpentan-1-ol, +3-methylpentan-2-ol, +2-methylpentan-3-ol, +3-methylpentan-3-ol, +2-methylpentan-2-ol, +4-methyl-pentan-2-ol, and +hexan-2-ol. Excess volumes were determined from density measurements made with a vibrating-tube densimeter. The V_m^E values were all positive, decreasing with the n value of the ester: C_n?1H_2n?1CO₂C₂H₅.     

Solid + liquid equilibria of (n-alkane + cyclohexane) mixtures at high pressures

Solid+liquid equilibria (SLE) of [n-alkanes (tridecane, hexadecane, octadecane, or eicosane) + cyclohexane] at very high pressures up to about 1.0 GPa have been investigated in the temperature range from 293 to 363 K using a thermostated apparatus for the measurements of transition pressures from the liquid to the solid state in two component isothermal solutions. The freezing temperature of each mixture increases monotonously with increasing pressure. The eutectic point of the binary systems shifts to a higher temperature and to a higher n-alkane concentration with increasing pressure. The pressure–temperature–composition relation of the high-pressure solid–liquid equilibria, a polynomial based on the general solubility equation at atmospheric pressure, was satisfactorily used. Additionally, the SLE of the binary system (tridecane+cyclohexane) at normal pressure was measured by the dynamic method. The results at high pressure for all systems were compared to that at normal pressure.     

Excess molar enthalpies of binary mixtures for (tributyl phosphate+methanol/ethanol) at 298.15 K

Excess molar enthalpies of binary mixtures for tributyl phosphate (TBP)+methanol/ethanol were measured with a TAM air Isothermal calorimeter at 298.15 K and ambient. The results for xTBP+(1–x)CH₃OH are negative in the whole range of composition, while the values for xTBP+(1–x)C₂H₅OH change from positive values at low x to small negative values at high x. The experimental results have been correlated with the Redlich–Kister polynomial. IR spectra of the mixtures were measured to investigate the effect of hydrogen bonding in the mixture.     

Excess molar enthalpies at 298.15 K of (cyclohexane + a methylquinoline) and of (benzene + a methylquinoline)

Excess molar enthalpies of (cyclohexane or benzene + 2-methylquinoline, +4-methylquinoline, + 6-methylquinoline, + quinoline, + 1-methylnaphthalene, and + 2-methylnaphthalene) were measured at 298.15 K (the mixtures with 2-methylnaphthalene were studied at 309.15 and 318.15 K). From the results for (cyclohexane + a methylquinoline), all of which are strongly positive, it is possible to show that CH₃N interactions follow the expected order in accordance with the distance between the groups in the molecule. Measurements on (benzene + a methylquinoline) cannot be satisfactorily correlated with the dipole moment of the methylquinoline. The different activity of the methyl group in accordance with its position in the molecule accounts for the calorimetric behaviour of most of the mixtures.     

Heat capacities and densities of mixtures of very polar substances. 3. Mixtures containing either trichloromethane or 1,4-dioxane or diisopropylether

Excess molar heat capacities C _P ^E at constant pressure and excess molar volumes V ^E have been determined, as a function of mole fraction x₁ at 25°C and atmospheric pressure, for 10 binary liquid mixtures containing either trichloromethane (series I) with C₆H₅CH₃, or C₆H₅Cl, or C₅H₅N, or CH₃COCH₃, or C₆H₅NO₂; 1,4-dioxane (series II) with (C₂H₅)₃N, or (CH₃)₂CHOCH(CH₃)₂, or (CH_{3 2}SO); or diisopropyl ether (di-1-methylethyl ether) (series III) with (C₂H₅)₃N, or CHCl₃. The dipole momentsp (10^–30C-m) of the substances range from nearly 0 to 14.1 for nitrobenzene. The C _P ^E of series I and III are all positive, with C _P ^E (x₁=0.5) (J-K^–1-mol^–1) ranging from 1.04 for {x₁CHCl₃+x₂C₆H₅Cl} to 16.66 for {x₁(CH₃)₂CHOCH(CH₃)₂+x₂CHCl₃}. In series II, the C _P ^E are positive and small for {x₁1,4-C₄H₈O₂+x₂(CH₃)₂CHOCH(CH₃)₂}, S-shaped and small for {x₁1,4-C₄H₈O₂+x₂(C₂H₅)₃N}, and negative and small for {x₁1,4-C₄H₈O₂+x₂(CH₃)₂SO}. The excess volumes are small and positive for {x₁CHCl₃+x₂C₆H₅CH₃}, S-shaped for {x₁CHCl₃+x₂CH₃COCH₃}, {x₁1,4-C₄H₈O₂+x₂(C₂H₅)₃N} and {x₁(CH₃)₂CHOCH(CH₃)₂+x₂(C₂H₅)₃N}, and negative for the other systems.Presented at the Symposium, 76^th CSC Congress, Sherbrooke, Quebec, May 30–June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65^th birthday     

Excess molar enthalpies of binary mixtures containing poly(ethylene glycol) 200+four cyclic ethers at (288.15, 298.15 and 313.15) K and at atmospheric pressure

Excess molar enthalpies, H_m^E, of binary mixtures containing poly(ethylene glycol) (PEG) 200+1,3-dioxolane, PEG 200+1,4-dioxane, PEG 200+oxolane and PEG 200+oxane were determined using a flow microcalorimeter at (288.15, 298.15 and 313.15) K and at atmospheric pressure. The H_m^E curves are always positive, with maxima varying from 393 J mol⁻¹ (1,3-dioxolane) to 658 J mol⁻¹ (oxolane), showing asymmetrical trends. The effect of the temperature is well marked on the calorimetric data that increase as the temperature is increased. The Redlich-Kister polynomial was used to estimate the binary fitting parameters. Root-mean-square deviations from the regression lines are reported.     

Chaleurs de melanges a 298.15 K du systeme ternaire cyclohexane (1) + benzene (2) + 1-chlorobutane (3)

Heats of mixingH ^E at 298.15 K and 1 atm are reported for the ternary liquid mixture of cyclohexane (1) + benzene (2) + 1-chlorobutane (3). A Redlich-Kister type of equation was used to represent and correlate the results.     

Excess enthalpies of binary mixtures containing poly(propylene glycols) + benzyl alcohol, or + m-cresol, or + anisole at 308.15 K and at atmospheric pressure

Excess enthalpies, H^E, of binary mixtures containing poly(propylene glycols) of different molecular masses + benzyl alcohol, or + m-cresol, or + anisole were determined using a flow microcalorimeter at 308.15 K and at atmospheric pressure. Data was correlated using the Redlich–Kister polynomial. Results were qualitatively discussed in terms of molecular interactions and of the regular solution model.     

Excess molar enthalpies of the ternary mixtures: methyl tert-butyl ether + 3-methylpentane + (n-decane or n-dodecane) at 298.15 K

Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for the two ternary mixtures formed by mixing either methyl tert-butyl ether with binary mixtures of 3-methylpentane and either n-decane or n-dodecane. Smooth representations of the ternary results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. It is found that the Liebermann and Fried model also provided good representation of the ternary results, using only the physical properties of the components and their binary mixtures.