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1.
The measurement of excess enthalpies, HE, at T=298.15 K and densities at temperatures between 283.15 K and 313.15 K are reported for the (2-methoxyethanol + 1,4-dioxane) and (1,2-dimethoxyethane + benzene) systems. The values of HE and the excess volumes, VE, are positive, and the temperature dependence of VE is quite small for (2-methoxyethanol + 1,4-dioxane). The (1,2-dimethoxyethane + benzene) system shows a negative HE and sigmoid curves in VE, which change sign from positive to negative with an increase in 1,2-dimethoxyethane. The temperature dependence of VE for this system is negative.  相似文献   

2.
Density ρ, viscosity η, and refractive index nD, values for (tetradecane + benzene, + toluene, + chlorobenzene, + bromobenzene, + anisole) binary mixtures over the entire range of mole fraction have been measured at temperatures (298.15, 303.15, and 308.15) K at atmospheric pressure. The speed of sound u has been measured at T = 298.15 K only. Using these data, excess molar volume VE, deviations in viscosity Δη, Lorentz–Lorenz molar refraction ΔR, speed of sound Δu, and isentropic compressibility Δks have been calculated. These results have been fitted to the Redlich and Kister polynomial equation to estimate the binary interaction parameters and standard deviations. Excess molar volumes have exhibited both positive and negative trends in many mixtures, depending upon the nature of the second component of the mixture. For the (tetradecane + chlorobenzene) binary mixture, an incipient inversion has been observed. Calculated thermodynamic quantities have been discussed in terms of intermolecular interactions between mixing components.  相似文献   

3.
Excess molar volumes VmEof {di- n -butyl ether (DBE)  +  a monofunctional organic compound} have been determined atT =  298.15 K over the whole composition range by means of a vibrating-tube densimeter. TheVmE values were either positive (propylamine, or butylamine, or acetone, or tetrahydrofuran  +  DBE) or negative (methanol, or butanol, or diethyl ether, or cyclopentanone, or acetonitrile  +  DBE). Markedly asymmetric VmEcurves were displayed by (DBE  +  methanol) and (DBE  +  acetonitrile). Partial molar volumes __ Vmoat infinite dilution in DBE, both from this work and the literature, were analysed in terms of an additivity scheme, and the group contributions thus obtained were discussed and compared with analogous results in water. DBE revealed a greater capability of distinguishing between polar and non-polar solutes, as well as in discriminating differently shaped molecules (unbranched, branched, cyclic). The limiting slopes of apparent excess molar volumes are evaluated and briefly discussed in terms of solute–solute and solute–solvent interactions.  相似文献   

4.
The excess molar volumes VmE at T=298.15 have been determined in the whole composition domain for (2-methoxyethanol + tetrahydrofuran + cyclohexane) and for the parent binary mixtures. Data on VmE are also reported for (2-ethoxyethanol + cyclohexane). All binaries showed positive VmE values, small for (methoxyethanol + tetrahydrofuran) and large for the other ones. The ternary VmE surface is always positive and exhibits a smooth trend with a maximum corresponding to the binary (2-methoxyethanol + cyclohexane). The capabilities of various models of either predicting or reproducing the ternary data have been compared. The behaviour of VmE and of the excess apparent molar volume of the components is discussed in both binary and ternary mixtures. The results suggest that hydrogen bonding decreases with alcohol dilution and increases with the tetrahydrofuran content in the ternary solutions.  相似文献   

5.
Excess molar enthalpies of (2- butanone  +  cyclohexane, or methylcyclohexane, or toluene, or chlorobenzene, or cyclohexanone) and excess molar heat capacities of (2- butanone  +  benzene, or toluene, or chlorobenzene, or cyclohexanone) were measured atT =  298.15 K. Aliphatic systems were endothermic and the chlorobenzene system was exothermic. On the other hand, the toluene system changed sign to be S-shaped similar to the benzene system reported by Kiyohara et al. The values of excess molar enthalpies of the present mixtures were slightly larger than the corresponding mixtures of cyclohexanone already reported. Excess molar heat capacities of aromatic systems were characteristically S-shaped for the mixture containing aromatics. The values of the present mixtures were less than the corresponding mixtures of cyclohexanone. The mixture (2-butanone  +  cyclohexanone) was endothermic forHmE and negative for Cp,mE.  相似文献   

6.
《Fluid Phase Equilibria》2005,235(1):42-49
Molar excess volumes and molar excess enthalpies of butyl acetate (i) with cyclohexane or benzene or toluene or o-, m- or p-xylene (j) binary mixtures have been measured dilatometrically and calorimetrically over the entire composition range at 308.15 K. The observed data have also been analyzed in terms of graph theoretical approach. The analysis of VE data by graph theoretical approach suggests that butyl acetate in pure state exists as associated entity and (i + j) mixtures are characterized by the presence of (ij) molecular entity. It has further been observed that VE and HE values calculated by this approach agree well with the corresponding experimental values. The presence of molecular entity is further confirmed by IR study of (i + j) mixture.  相似文献   

7.
The densities of (heptane + 1-chlorobutane, or 1-chloropentane, or 1-chlorohexane) were measured at the temperatures (308.15, 318.15, and 328.15) K by means of a vibrating-tube densimeter. The excess molar volumes, VmE, calculated from the density data, along with our previous data(1) determined at T=298.15 K for the same systems, provide the temperature dependence of VmE in the temperature range of 298 to 328 K. The VmE results were correlated using the fourth-order Redlich–Kister equation, with the maximum likelihood principle applied for the determination of the adjustable parameters. It was found that the deviations from ideal behaviour (both positive and negative) in the systems studied increase with increasing temperature.  相似文献   

8.
The vapour pressures of liquid {3-diethylaminopropylamine (3-DEPA) + cyclohexane} were measured by a static method between T = (273.15 and 363.15) K at 10 K intervals. The excess molar volumes VE at 298.15 K and excess molar enthalpies HE at 303.15 K were also measured. The molar excess Gibbs free energies GE were obtained with Barker’s method and fitted to the Redlich–Kister equation. The Wilson equation was also used. Deviations between experimental and predicted GE and HE, by using DISQUAC model, were evaluated  相似文献   

9.
Volumetric properties of N-methyl-2-pyrrolidone (NMP) binary mixtures with γ-butyrolactone (GBL) and propylene carbonate (PC) are calculated from the experimental densities and reported in the temperature range from (293.15 to 323.15) K and at atmospheric pressure (0.1 MPa) over the whole composition range. The excess molar volumes have positive values in the whole concentration range in the case of (NMP + PC) binary mixture, with maximum value at equimolar composition, indicating weaker interactions between the components after the mixing. Two extreme VE values are observed in (NMP + GBL) system: maximum at x(NMP) = 0.4 and minimum at x(NMP) = 0.9. Negative VE values in NMP-rich region are the consequence of the better geometrical fit of the molecules. The excess properties of (NMP + GBL) and (NMP + PC) binaries are analyzed using Prigogine–Flory–Paterson theoretical model. An excellent agreement between experimental and theoretical values at equimolar composition is observed. Apparent molar volumes and thermal expansion coefficients are also calculated. Viscosity measurements of the pure components and NMP binary mixtures with GBL and PC were performed in the temperature range from (298.15 to 323.15) K. Using obtained experimental viscosities several semi-empirical equations and models were tested.  相似文献   

10.
Vapour pressure data were measured for three binary systems containing water, methanol or ethanol with an ionic liquid (IL) 1-ethyl-3-ethylimidazolium diethylphosphate([EEIM][DEP]) and for three ternary systems, i.e. (water + ethanol + [EEIM][DEP]), (water  + methanol + [EEIM][DEP]), and (ethanol + methanol + [EEIM][DEP]), at varying temperature and IL-content ranging from mass fraction of 0.10 to 0.85 by a quasi-static method. The vapour pressure data of the binary systems were correlated by NRTL equation with average absolute relative deviation (ARD) within 0.0091. The binary NRTL parameters were used to predict the vapour pressure of the ternary systems (ethanol + water + [EEIM][DEP]), (water + methanol + [EEIM][DEP]), and (ethanol +  methanol + [EEIM][DEP]) with an overall ARD of 0.037 and the maximum deviation of −0.1295. The results indicate that ionic liquid [EEIM][DEP] can give rise to a negative deviation from the Raoult’s law for the solvents of water, methanol and ethanol, but to a varying degree leading to the variation of relative volatility of a solvent and even removal of azeotrope for (water + ethanol).  相似文献   

11.
Excess molar volumes VE at 298.15 K were determined by means of a vibrating tube densimeter for binary mixtures of heptane + primary n-alkyl (C3 to C10) and branched amines (iso-propyl-, iso-, sec-, and tert-butyl-, iso-, tert-pentyl-, and pentan-3-amine) in the whole composition range. The apparent molar volumes of solid dodecyl- and tetradecylamine in heptane dilute solution were also determined. The VE values were found positive for mixtures involving C3 to C8 linear amines, with VE decreasing with chain lengthening. Heptane + nonyl and decylamine showed s-shaped, markedly asymmetric, curves. Mixtures with branched C3 to C5 amines displayed positive VE’s larger than those observed in the mixtures of the corresponding linear isomers. Partial molar volumes V° at infinite dilution in heptane were evaluated for the examined amines and compared with those of alkanes and alkanols taken from the literature. An additivity scheme, based on the intrinsic volume approach, was applied to estimate group (CH3, CH2, CH, C, NH2, and OH) contributions to V°. The effect of branching on V° and the limiting slope of the apparent excess molar volumes were evaluated and discussed in terms of solute–solvent and solute–solute interactions.  相似文献   

12.
13.
Densities and viscosities of binary liquid mixtures of (1-hexanol  + n -hexane, or cyclohexane, or benzene) have been measured at a number of mole fractions at T =  (303, 313, and 323) K. The excess molar volume VmEand apparent molar volume Vφhave been calculated from the density data. TheVmE anddVmE / dT for the system, (1-hexanol  + n -hexane) have been found negative, while those for the systems, (1-hexanol  +  cyclohexane) and (1-hexanol  +  benzene), were found to be positive. Excess viscosities ηEcalculated from viscosity data, have been found to be negative over the whole composition range at the temperatures studied for all the three systems. Volumetric and viscometric behaviours indicate that dispersion is the major force of interaction between the components in (1-hexanol  +  cyclohexane, or benzene), while inclusion of hydrocarbon chains into the interstices of polymolecular ring structures of alcohol formed by hydrogen bonding has been assumed to play a significant role apart from dispersion in the system (1-hexanol  + n -hexane). Thermodynamic parameters of activation for viscous flow have been calculated from the viscosity data at different temperatures and a possible explanation suggested.  相似文献   

14.
The densities of (o-xylene, or m-xylene, or p-xylene + dimethyl sulfoxide) were measured at temperatures (293.15, 303.15, 313.15, 323.15, 333.15, 343.15, 353.15) K and atmospheric pressure by means of a vibrating-tube densimeter. The excess molar volume VmE calculated from the density data provide the temperature dependence of VmE in the temperature range of (293.15 to 353.15) K. The VmE results were correlated using the fourth-order Redlich–Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters. Also we have calculated partial molar volume and excess partial molar volumes of two components. It was found that the VmE in the systems studied increase with rising temperature.  相似文献   

15.
The vapor pressures of (ethanol + glycerol) and (water + glycerol) binary mixtures were measured by means of two static devices at temperatures between (273 and 353 (or 363)) K. The data were correlated with the Antoine equation. From these data, excess Gibbs free energy functions (GE) were calculated for several constant temperatures and fitted to a fourth-order Redlich–Kister equation using the Barker method. The (ethanol + glycerol) binary system exhibits positive deviations in GE where for the (water + glycerol) mixture, the GE is negative for all temperatures investigated over the whole composition. Additionally, the NRTL, UNIQUAC and Modified UNIFAC (Do) models have been used for the correlation or prediction of the total pressure.  相似文献   

16.
Mutual solubility data of the binary (methanol + limonene) mixture at the temperatures ranging from 288.15 K close to upper critical solution temperature, and ternary (liquid + liquid) equilibrium (tie-lines) of the (methanol + ethanol + limonene) mixture at the temperatures (288.15, 298.15, and 308.15) K have been obtained. The experimental results have been represented accurately in terms of the extended and modified UNIQUAC models with binary parameters, compared with the UNIQUAC model. The temperature dependence of binary and ternary (liquid + liquid) equilibrium for the binary (methanol + limonene) and ternary (methanol + ethanol + limonene) mixtures could be calculated successfully using the extended and modified UNIQUAC model.  相似文献   

17.
Excess molar enthalpies HmEand excess molar volumesVmE of (1,3-dimethyl-2-imidazolidinone  +  benzene, or methylbenzene, or 1,2-dimethylbenzene, or 1,3-dimethylbenzene, or 1,4-dimethylbenzene, or 1,3,5-trimethylbenzene, or ethylbenzene) over the whole range of compositions have been measured at T =  298.15 K. The excess molar enthalpy values were positive for five of the seven systems studied and the excess molar volume values were negative for six of the seven systems studied. The excess enthalpy ranged from a maximum of 435 J · mol  1for (1,3-dimethyl-2-imidazoline  +  1,3,5-trimethylbenzene) to a minimum of   308 J · mol  1for (1,3-dimethyl-2-imidazoline  +  benzene). The excess molar volume values ranged from a maximum of 0.95cm3mol  1 for (1,3-dimethyl-2-imidazoline  +  ethylbenzene) and a minimum of   1.41 cm3mol  1for (1,3-dimethyl-2-imidazoline  +  methylbenzene). The Redlich–Kister polynomial was used to correlate both the excess molar enthalpy and the excess molar volume data and the NRTL and UNIQUAC models were used to correlate the enthalpy of mixing data. The NRTL equation was found to be more suitable than the UNIQUAC equation for these systems. The results are discussed in terms of the polarizability of the aromatic compound and the effect of methyl substituents on the benzene ring.  相似文献   

18.
Densities and viscosities of the pure ionic liquid 1-methylimidazolium acetate ([Mim]Ac) and its binary mixtures with methanol, ethanol, 1-propanol, and 1-butanol were measured at temperature ranging from T = (293.15 to 313.15) K. The thermal expansion coefficient, molecular volume, standard entropy, and lattice energy of [Mim]Ac were deduced from the experimental density results. A simple linear equation was used to correlate the variation of viscosity of [Mim]Ac with temperature. Excess molar volumes VE and viscosity deviations Δη for the binary mixtures at above mentioned temperature were calculated and fitted to the Redlich–Kister equation with satisfactory results. Excess molar volumes for {[Mim]Ac + 1-butanol} mixture have an S shape, while those for other mixtures have a negative deviation from ideal behaviour over the entire mole fraction range. Viscosity deviations are all negative deviation for {[Mim]Ac + alcohol} mixtures. The results were interpreted in terms of interactions and structural factors of binary mixtures.  相似文献   

19.
Densities of binary mixtures of N,N-dimethylacetamide (DMA) with water (H2O) or water-d2 (D2O) were measured at the temperatures from T=277.13 K to T=318.15 K by means of a vibrating-tube densimeter. The excess molar volumes VmE, calculated from the density data, are negative for the (H2O + DMA) and (D2O + DMA) mixtures over the entire range of composition and temperature. The VmE curves exhibit a minimum at x(DMA)≅0.4. At each temperature, this minimum is slightly deeper for the (D2O + DMA) mixtures than for the corresponding (H2O + DMA) mixtures. The difference between D2O and H2O systems becomes smaller when the temperature increases. The VmE results were correlated using a modified Redlich–Kister expansion. The partial molar volume of DMA plotted against x(DMA) goes through a sharp minimum in the water-rich region around x(DMA)≅0.08. This minimum is more pronounced the lower the temperature and is deeper in D2O than in H2O at each temperature. Again, the difference becomes smaller as the temperature increases. The excess expansion factor αE plotted against x(DMA) exhibit a maximum in the water rich region of the mole fraction scale. At each temperature, this maximum is higher for the (D2O + DMA) mixtures than for the corresponding (H2O + DMA) mixtures, and the difference becomes smaller as the temperature increases. At its maximum, αE can be even more than 25 per cent of total value of the cubic expansion coefficient α in the (H2O + DMA) and (D2O + DMA) mixtures.  相似文献   

20.
Densities, ρ, and viscosities, η, of aqueous solutions of N-(2-hydroxyethyl)morpholine were measured over the entire composition range at T = (293.15, 303.15, 313.15, 323.15, 333.15) K and at atmospheric pressure. The excess molar volumes VE and viscosity deviations ηE of aqueous solutions were calculated from the experimental results of density and viscosity measurements and fitted to the Redlich–Kister polynomial equation. Apparent molar volumes V?, partial molar volume at infinite dilution V, and the thermal expansion coefficient α were also calculated. The VE values were found to be negative over the entire composition range at all temperatures studied and become less negative with increasing temperature, whereas the viscosity data ηE exhibited positive deviations from ideal behaviour.  相似文献   

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