Excess molar volumes and viscosities of binary mixtures of cyclohexane and n-alkane at 298.15 K

Awwad, A.M. and Salman, M.A., 1986. Excess molar volumes and viscosities of binary mixtures of cyclohexane and n-alkane at 298.15 K. Fluid Phase Equilibria, 25: 195-208.Excess molar volumes, viscosities, excess molar viscosities, and excess molar activation energies of viscous flow were determined for binary mixtures of cyclohexane + n-pentane, + n-hexane, + n-heptane, + n-octane, + n-nonane, + n-decane, + n-dodecane, + n-tetradecane and + n-hexadecane at 298.15 K. The effect of orientational order of n-alkane on solution molar volumes and viscosities is investigated as well as the adequacy of the Flory theory and free volume theories used to predict solution molar volumes and viscosities. For longer n-alkanes V^E, η^E and ΔG*^E are positive and associated with the orientational order.     

The excess volumes of decahydronaphthalene + cyclopentane, + cyclohexane, + cycloheptane and + cyclooctane at two temperatures

The excess volumes of decahydronaphthalene (decalin) + cyclopentane, + cyclohexane, + cycloheptane and + cyclooctane have been measured over the whole composition range at two temperatures. These measurements show many similarities to the V_m^E results of bicyclohexyl + a cycloalkane and 1,2,3,4-tetrahydronaphthalene (tetralin) + a cycloalkane.     

Excess enthalpies of decahydronaphthalene in cycloalkanes and inn-Alkanes at two temperatures

The H _m ^E of decahydronaphthalene in cyclopentane, cyclohexane, cycloheptane, cyclooctane, n-hexane, n-heptane, n-octane, n-dodecane and in n-hexadecane have been measured over the whole composition range at two temperatures. These results together with previously reported V _m ^E results for the same systems have been fitted to the Flory theory of liquid mixtures.     

Calorimetric effects of short-range orientational order in solutions of benzene or n-alkylbenzenes in n-alkanes

A Picker flow microcalorimeter was used to determine molar excess heat capacities, C^E_p, at 298.15 K, as function of concentration, for the eleven liquid mixtures: benzene+n-tetradecane; toluene+n-heptane, and +n-tetradecane; ethylbenzene+n-heptane, +n-decane, +n-dodecane; and +n-tetradecane; n-propylbenzene +n-heptane, and +n-tetradecane; n-butylbenzene+n-heptane, and +n-tetradecane. In addition, molar excess volumes, V^E, at 298.15 K, were obtained for each of these systems (except benzene+n-tetradecane) and for toluene+n-hexane. The excess volumes which are generally negative with a short alkane, increase and become positive with increasing chain length of the alkane. The excess heat capacities are negative in all cases. The absolute ¦C^E_p¦ increased with increasing chain length of the n-alkane. A formal interchange parameter, C_p12, is calculated and its dependence on n-alkane chain length is discussed in terms of molecular orientations.     

Excess molar volumes at 298.15 K of binary liquid organic mixtures containing n-alkanones and linear ethers: Application of Flory’s theory

Excess molar volumes, V_m^E, at 298.15 K and atmospheric pressure over the entire composition range for binary mixtures of 2-butanone with di-n-butyl ether and 2-pentanone and 3-pentanone with di-n-butyl ether and 2,5-dioxahexane, 2-heptanone and 4-heptanone with di-n-butyl ether, 2,5-dioxahexane and 3,6,9-trioxaundecane are reported from densities measured with a vibrating-tube densimeter. All the excess volumes present strong contractions when compared to those of n-alkanone+n-alkane systems.Molar excess enthalpies H_m^E and V_m^E of the considered mixtures vary similarly. This may be attributed to interactional effects which prevail over structural effects.Flory’s theory has been applied to the systems under study. As expected, results for H_m^E are better when the difference in polarity of the components of the mixture decreases. V_m^E is often poorly represented.     

Interaction of cyclopentane with benzene,carbon tetrachloride and cyclohexane

Heats of mixing cyclopentane + benzene, + carbon tetrachloride, + cyclohexane at 308.15 K and for cyclohexane + carbon tetrachloride at 298.15 K have been determined in an adiabatic calorimeter. The data have been examined for current theories (McGlashan, Flory and Barker) of solutions and show that McGlashan's theory predicts values for H^E and G^E that are in good agreement with their corresponding experimental values. Interaction energy between the components of these mixtures has also been determined.     

Thermodynamic properties of (a pentyl ester + an-alkane). XIV. The HmEand VmEfor (an ester + an-alkane)

This paper presents experimental data for the excess molar enthalpies H_m^Eand excess molar volumes V_m^Eat T =  298.15 K and atmospheric pressure for 21 binary mixtures consisting of one of three pentyl esters (ethanoate, propanoate, and pentanoate) and one of seven odd n -alkanes (from pentane to heptadecane). The results have shown the mixing of these mixtures to be endothermic, with H_m^Evarying uniformly with the n -alkane chain length. The variation of V_m^Ewas also found to be uniform, with contraction effects observed for the mixtures that contained low molecular-weight hydrocarbons, and increasing with the pentyl ester chain length. Different group-contribution theories were used to calculate the excess properties for (an ester  +  an n -alkane). Comparison of the calculated and experimental results revealed that, in most cases, the differences increased with the molecular weight of the components. However, the differences for the calculated values of the excess volumes using the model of Nitta et al. decreased with n -alkane chain length but increased with ester chain length, the mean differences for the excess volumes being larger than 20 per cent.     

Liquid Solution Densities of Ternary-Pseudobinary Mixtures of (Benzene + Cyclohexane) in the Presence of Tetrachloromethane or <Emphasis Type="Italic">n</Emphasis>-Hexane

Densities have been obtained as a function of composition for ternary-pseudobinary mixtures of [(benzene + tetrachloromethane or n-hexane) + (cyclohexane + tetrachloromethane or n-hexane)] at atmospheric pressure and the temperature 298.15 K, by means of a vibrating-tube densimeter. Excess molar volumes, V_m^E, partial molar volumes and excess partial molar volumes were calculated from the density data. The values of V_m^E have been correlated using the Redlich–Kister equation and the coefficients and standard errors were estimated. The experimental and calculated quantities are used to discuss the mixing behavior of the components. The results show that the third component, CCl₄ or n-C₆H₁₄, have quite different influences on the volumetric properties of binary liquid mixtures of benzene with cyclohexane.     

Enthalphy of mixing of bromobenzene with n-alkanes,with cyclohexane,and with benzene

A dynamic flow microcalorimeter of the Picker design was used to measure enthalpies of mixing at 298.15 K and atmospheric pressure of the six binary systems bromobenzene + n-hexane, + n-heptane, + n-nonane, + n-tetradecane, + cyclohexane, and + benzene. Within the homologous series of n-alkane systems, the interaction parameter, h₁₂, calculated from rigid-lattice group contribution theory, decreases weakly with increasing chain length of the alkane. This behavior is quite analogous to that observed with chloro-derivatives of benzene + n-alkane.     

Excess magnitudes for the benzene + n-dodecane system at 298.15 and 323.15 K

The vapor pressures for benzene + n-dodecane mixtures have been measured using a static apparatus. Values for the excess Gibbs energy have been calculated using a modified form of Barker's method and fitted to a Padé approximant equation. Selection of the most adequate approximant is made according to objective criteria. The results are compared with those corresponding to other benzene + n-alkane systems. The values for the activity coefficient of benzene at infinite dilution calculated from these data agrees very well with the values obtained by gas-liquid chromatography.     

The excess enthalpies of (carbon dioxide + cyclohexane) at 308.15, 358.15, and 413.15 K from 7.50 to 12.50 MPa

The excess molar enthalpies H_m^E for (carbon dioxide + cyclohexane) were measured in the vicinity of their critical locus and in the supercritical region. Mixtures at 308.15 K and at 7.50 MPa show very exothermic mixing and a region where H_m^E varies linearly with mole fraction x while at 10.50 and 12.50 MPa they show only moderately endothermic mixing. Mixtures at 358.15 and 413.15 K and at all pressures studied except for 358.15 K and 12.50 MPa have an exothermic section in the cyclohexane-rich region, a linear section which starts at a mole fraction x corresponding very closely to that of the minimum value of H_m^E, and an endothermic section in the carbon-dioxide-rich region. The H_m^E results exhibiting a linear section allow the determination of values for the vapor and liquid equilibrium-phase compositions. The changes observed in the excess enthalpy with both pressure and temperature are discussed in terms of liquid-vapor equilibrium and critical constants for (carbon dioxide + cyclohexane).     

Experimental liquid–liquid equilibria of 1-methylimidazole with hydrocarbons and ethers

The liquid–liquid equilibria (LLE) of eight binary systems containing 1-methylimidazole and n-alkanes (n-pentane, n-hexane), cyclohydrocarbons (cyclopentane, cyclohexane), aromatic hydrocarbons (hexylbenzene) or ethers (di-n-propyl ether, di-n-butyl ether, di-n-pentyl ether) have been measured from 270 K to the boiling temperature of the solvent using a “cloud point” method. Experimental solubility results are compared with values calculated by means of the NRTL equation utilizing parameters derived from LLE results.Solubility of 1-methylimidazole in many other organic solvents (aromatic hydrocarbons, branch chain ethers and ketones) has been measured at temperatures higher than 293 K and no miscibility gap was observed. The interaction of 1-methylimidazole with different solvents is discussed.     

Activity coefficients of hydrocarbon solutes at infinite dilution in the ionic liquid, 1-methyl-3-octyl-imidazolium chloride from gas–liquid chromatography

Activity coefficients for hydrocarbon solutes at infinite dilution in 1-methyl-3-octyl-imidazolium chloride have been measured using the medium pressure gas–liquid chromatography method. The hydrocarbon solutes used were n-pentane, n-hexane, n-heptane, n-octane, 1-hexene, 1-heptene, 1-octene, 1-hexyne, 1-heptyne, 1-octyne, cyclopentane, cyclohexane, cycloheptane, benzene, and toluene. Activity coefficients at infinite dilution were determined at the following three temperatures (298.15, 308.15, and 318.15) K. Selectivities for benzene and the hydrocarbons are presented and the results indicate that 1-methyl-3-octyl-imidazolium chloride is a reasonable solvent for the separation of an alkane or an alkene from benzene.     

Correlation of the prigogine-flory theory with isothermal compressibility data. I. Systems with quasi-spherical molecules

The isothermal compressibilities K_T for cyclohexane + benzene, cyclohexane + toluene and benzene + toluene systems at 25, 35, 45 and 60°C have been used to test the Prigogine-Flory theory using Van der Waals and Lennard-Jones energy potentials. Flory's energy parameter X ₁₂ was calculated for these systems at the four temperatures. From X ₁₂ for the equimolar mixture, the following excess functions were calculated: (?V^E/?_p)_T which is related to K _T ^E , the heat of mixing H ^E , and the excess volume V ^E . The theory and any of the two potentials give (?V^E/?_p)_T which fit the experimental data, but H ^E and V ^E , calculated using the same X ₁₂ parameter, depart appreciably from the experimental data even though they agree in sign and have the essential features of the excess functions. The departure is apparent in both magnitude (in particular for the cyclohexane + benzene, and cyclohexane + toluene systems) and in the temperature dependence. The conclusion is that the X ₁₂ parameter does not predict the thermodynamic properties of these systems and the Lennard-Jones potential, involving a more complicated expression, does not contribute any improvement over the Van der Waals potential.     

Oriented interaction between naphthalene and alkane molecules: Theoretical interpretation of spectral shifts of ππ* bands of aromatic hydrocarbons in alkane solvents

Several features of the spectral shifts of ππ^* bands for aromatic hydrocarbons dissolved in n-alkane solvents have been explained by the existence of preferred relative orientations between the aromatic hydrocarbon and the n-alkane molecules. Theoretical evaluation of the interaction energy between naphthalene and n-pentane or n-octane actually display two preferred orientations. Moreover, these orientations are identical with those proposed, on steric grounds, for explaining the adsorption of alkanes on graphitic basal planes as proposed by Groszek.     

Effects of the Presence of Cyclohexane or Methylcyclohexane on the Densities and Volumetric Properties of the Mixture (Benzene + Propionitrile)

Excess molar volumes, V_m^E, have been obtained as a function of composition for ternary-pseudobinary mixtures of [(benzene + cyclohexane or methylcyclohexane) + (propionitrile + cyclohexane or methylcyclohexane)] from the densities measured by means of a vibrating-tube densimeter at atmospheric pressure and a temperature of 298.15 K. The values of V_m^E have been correlated using the Redlich–Kister equation to estimate the coefficients and standard errors. The experimental and calculated quantities are used to discuss the mixing behavior of the components. The results show that the third component, cyclohexane or methylcyclohexane, has a significant effect on the interaction between benzene and propionitrile.     

Liquid–liquid equilibria for the ternary system water+n-dodecane+2-(2-n-hexyloxyethoxy)ethanol

Experiments of the fish-shaped phase diagram for the ternary system water+n-dodecane+2-(2-n-hexyloxyethoxy)ethanol (abbreviated by C₆E₂ hereafter) under atmospheric pressure were performed at constant water/n-dodecane weight ratio (1/1) to locate the critical end points. The upper and lower critical consolute temperatures for the system of interest are 307.80 K and 282.30 K, respectively. Compositions of two- and three-phase liquid–liquid equilibrium for the ternary system water+n-dodecane+C₆E₂ at 293.15 K and 303.15 K under atmospheric pressure are presented in this paper.     

Excess volumes for binary liquid mixtures of trichloroethylene with anisole,pyridine, quinoline and cyclohexane at 298.15 and 308.15 K

Dilatometric measurements of excess volumes V^E have been made for binary liquid mixtures of trichloroethylene (CHClCCl₂) with anisole, pyridine, quinoline and cyclohexane at 298.15 and 308.15 K. At both temperatures, and values of V^E have been found to be slightly negative for CHClCCl₂ + anisole, CHClCCl₂ + pyridine, highly negative for CHClCCl₂ + quinoline, and highly positive for CHClCCl₂ + cyclohexane. The negative values of V^E for the systems CHClCCl₂ + anisole, CHClCCl₂ + pyridine, and CHClCCl₂ + quinoline, have been explained as due to the existence of specific interaction of CHClCCl₂ with anisole, pyridine and quinoline in the liquid state.     

Ultrasonic behaviour of methyl methacrylate+hydrocarbon mixtures at 298.15 and 308.15 K

The excess isentropic compressibilities, K_s^E for seven binary mixtures of methyl methacrylate+benzene, +o-xylene, +m-xylene, +p-xylene, +toluene, +ethylbenzene and +cyclohexane were estimated from the measured densities and speeds of sound at 298.15 and 308.15 K. The K_s^E values were large and positive for MMA+cyclohexane and +m-xylene, while they were negative for other mixtures. A qualitative analysis of K_s^E values was made in terms of molecular interactions. The speeds of sound of all the mixtures were also predicted from the free length theory (FLT) and collision factor theory (CFT).