Density,speed of sound,heat capacity,and related properties of 1-hexanol and 2-ethyl-1-butanol as function of temperature and pressure

The speeds of sound in 1-hexanol and 2-ethyl-1-butanol have been measured over the temperature range from (293.15 to 318.15) K and at pressures up to 101 MPa. The densities have been measured within the temperature range from (283.15 to 343.15 or 353.15) K under atmospheric pressure. For the measurements, a pulse-echo-overlap method and a vibrating tube densimeter have been used. Additionally, in the case of 2-ethyl-1-butanol, the isobaric heat capacities from T = (293.15 to 323.15) K at atmospheric pressure have been measured by means of a DSC calorimeter. The experimental results are then used to calculate the densities and isobaric heat capacities as a function of temperature and pressure by means of a numerical integration technique. The effects of pressure and temperature on these and the related properties are discussed. Densities are correlated by means of the Tait equation.     

The pρT behaviour of the lactate family

The densities of methyl lactate, ethyl lactate and butyl lactate have been measured using a high-pressure, high-temperature vibrating tube densimeter system over a temperature range from T = (283.15 to 338.15) K and a pressure range from p = (0.1 to 60.0) MPa. The experimental densities have been satisfactorily correlated with temperature and pressure using the TRIDEN equation. Finally, from the experimental densities, properties such as isobaric expansibility and isothermal compressibility have been calculated.     

Volumetric properties under pressure for the binary system ethanol + toluene

The density of the asymmetrical binary system composed of ethanol and toluene has been measured under pressure using a vibrating tube densimeter. The measurements have been performed for nine different compositions including the pure compounds at eight temperatures in the range 283.15–353.15 K and ten isobars up to 45 MPa. The uncertainty in the measured densities is estimated to be 0.1 kg m⁻³. The measured data has been used to study the behavior and influence of temperature, pressure and composition on the isothermal compressibility, the isobaric thermal expansion, and the excess molar volume. At several temperatures the isobaric thermal expansion shows an non-monotonical behavior versus composition, whereas the excess molar volumes reveal a complex sigmoid behavior. These results have been interpreted as changes in the free-volume and as the formation and weakening of the molecular interactions. The VLE behavior of this binary system within the considered temperature range is represented satisfactory by the perturbed-chain statistical association fluid theory (PC-SAFT) equation of state with a single interaction parameter, although no cross association between ethanol and toluene is taken into account. The densities of this binary system (pure compounds and mixtures) are satisfactory predicted by PC-SAFT with an overall AAD of 0.8%, but the behavior of the excess molar volume is not described correctly.     

Densities,excess volumes,isobaric expansivity,and isothermal compressibility of the (1-ethyl-3-methylimidazolium ethylsulfate + methanol) system at temperatures (283.15 to 333.15) K and pressures from (0.1 to 35) MPa

Densities of pure 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid – [C₂mim][EtSO₄] and its mixtures with methanol have been measured with an accuracy of ±0.2 kg · m^?3, over the temperature range (283.15 to 333.15) K and pressure range (0.1 to 35) MPa, using a vibrating tube densimeter. Excess volumes have been calculated directly from the experimental densities. The latter data have been correlated by the Tait equation with the temperature dependent parameters for the pure ionic liquid and by a van Laar-type equation, involving parameters dependent on temperature and pressure for the mixtures. The isobaric expansivity, isothermal compressibility, and related excess properties have been calculated. The exceptionally strong influence of pressure and temperature on these properties has been observed.     

Study of the volumetric properties of weakly associated alcohols by means of high-pressure speed of sound measurements

The speed of sound in the temperature (303.15 to 373.15) K and pressure range (0.1 to 100) MPa was measured for the liquid 3-pentanol, 3-methyl 3-pentanol, and 3-ethyl-3-pentanol. These results combined with the densities and isobaric heat capacity at atmospheric pressure obtained from the literature were used to calculate the density, and the isentropic and isothermal compressibilities in the same range of pressure and in the temperature interval (303.15 to 368.15) K by means of a predictor-corrector algorithm.     

Thermodynamic characterization of the mixture (1-butanol + iso-octane): Densities,viscosities, and isobaric heat capacities at high pressures

The densities at high pressures of 1-butanol and iso-octane were measured in the range (0.1 to 140) MPa at seven different temperatures, from (273.15 to 333.15) K, and their mixtures were measured in the range (0.1 to 50) MPa at four different temperatures, from (273.15 to 333.15) K. The measurements were performed in a high-pressure vibrating tube densimeter. The pressure–volume–temperature behavior of these compounds and their mixtures was evaluated accurately over a wide range of temperatures and pressures. The data were successfully correlated with the empirical Tamman–Tait equation. The experimental data and the correlations were used to study the behavior and the influence of temperature and pressure on the isothermal compressibility and the isobaric thermal expansivity.Also, the isobaric heat capacities were measured over the range (0.1 to 25) MPa at two different temperatures (293.15 and 313.15) K for the pure compounds and their mixtures. The measurements were performed in a high-pressure automated flow calorimeter. The excess molar heat capacities were assessed for the mixture and a positive deviation from the ideality was obtained.     

Thermodynamic properties of mixtures of N-methyl-2-pyrrolidinone and methanol at temperatures between 298.15 K and 343.15 K and pressures up to 60 MPa

We report measurements of the speed of sound in mixtures of N-methyl-2-pyrrolidinone and methanol at temperatures between 298.15 K and 343.15 K and at pressures up to 60 MPa. The measurements were made using a dual path pulse-echo apparatus operating at a frequency of 5 MHz. We have also measured the isobaric specific heat capacity of each mixture as a function of temperature at ambient pressure, by means of a Setaram DSC III microcalorimeter. The experimental results have been combined with literature data for the density of the same mixtures as a functions of temperature at ambient pressure to obtain the density, isobaric specific heat capacity, and other thermodynamic properties at temperatures between 298.15 K and 343.15 K and at pressures up to 60 MPa. Detailed comparisons with the literature data are presented.     

Liquid density of HFE-7200 and HFE-7500 from T = (283 to 363) K at pressures up to 100 MPa

The liquid densities of HFE-7200 (1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane, CAS Registry Number: 163702-05-4) and HFE-7500 (3-ethoxyperfluoro(2-methylhexane), CAS Registry Number: 297730-93-9) have been measured over the temperature range from (283 to 363) K and pressures up to 100 MPa by using a high pressure vibrating-tube densimeter. R134a has been used as a reference fluid to validate the densimeter. The uncertainty of each obtained datum was estimated, and the maximum expanded uncertainty with a level of confidence of 0.95 (k = 2) of density measurement for HFE-7200 and HFE-7500 were 0.04% and 0.03%, respectively. The measured liquid densities were correlated with the modified Tait equation and the maximum deviation is less than 0.03%. The isothermal compressibility and isobaric thermal expansivity were also calculated.     

Densities and volume properties of (water + tert-butanol) over the temperature range of (274.15 to 348.15) K at pressure of 0.1 MPa

The densities of {water (1) + tert-butanol (2)} binary mixture were measured over the temperature range (274.15 to 348.15) K at atmospheric pressure using “Anton Paar” digital vibrating-tube densimeter. Density measurements were carried out over the whole concentration range at (308.15 to 348.15) K. The following volume parameters were calculated: excess molar volumes and thermal isobaric expansivities of the mixture, partial molar volumes and partial molar thermal isobaric expansivities of the components. Concentration dependences of excess molar volumes were fitted with Redlich–Kister equation. The results of partial molar volume calculations using four equations were compared. It was established that for low alcohol concentrations at T ? 208 K the inflection points at x₂ ≈ 0.02 were observed at concentration dependences of specific volume. The concentration dependences of partial molar volumes of both water and tert-butanol had extremes at low alcohol content. The temperature dependence of partial molar volumes of water had some inversion at х₂ ≈ 0.65. The temperature dependence of partial molar volumes of tert-butanol at infinite dilution had minimum at ≈288 K. It was discovered that concentration dependences of thermal isobaric expansivities of the mixture at small alcohol content and low temperatures passed through minimum.     

Densities,excess molar volume,isothermal compressibility,and isobaric expansivity of (dimethyl carbonate + n-hexane) systems at temperatures (293.15 to 313.15) K and pressures from 0.1 MPa up to 40 MPa

The densities of dimethyl carbonate, n-hexane and their mixtures were measured for 12 compositions at five different temperatures varying from (293.15 to 313.15) K and over the pressure range of (0.1 to 40) MPa. The densities of pure substances and their mixtures at atmospheric pressure were measured by a vibrating-tube densimeter. The densities at high pressures were measured by a variable-volume autoclave and precise analytical balance. The excess molar volume, isothermal compressibility, and isobaric expansivity were derived from the experimental densities.     

Density measurements of liquid 2-propanol at temperatures between (280 and 393) K and at pressures up to 10 MPa

Liquid densities for 2-propanol have been measured at T = (280, 300, 325, 350, 375, and 393) K from about atmospheric pressure up to 10 MPa using a vibrating tube densimeter. The period of vibration has been converted into density using the Forced Path Mechanical Calibration method. The R134a has been used as reference fluid for T ? 350 K and water for T > 350 K. The uncertainty of the measurements is lower than ±0.05%. The measured liquid densities have been correlated with a Starling BWR equation with an overall AAD of 0.025%. The same BWR equation agrees within an AAD lower than 0.2% with the experimental values available in the literature over the same temperature and pressure range.     

Thermodynamic and acoustic properties of (heptane + dodecane) mixtures under elevated pressures

The speed of sound in (heptane + dodecane) mixtures was measured over the whole concentration range at pressures up to 101 MPa and within the temperature range from (293 to 318) K. The density of (heptane + dodecane) was measured in the whole composition range under atmospheric pressure and at temperatures from (293 to 318) K. The densities and heat capacities of these binaries at the same temperatures were calculated for pressures up to 100 MPa from the speeds of sound under elevated pressures together with the densities and heat capacities at atmospheric pressure. The effects of pressure and temperature on the excess molar volume and the excess molar heat capacity are discussed.     

Volumetric properties of itaconic acid aqueous solutions

Densities of itaconic acid aqueous solutions were measured at 5 K intervals from T = (278.15 to 343.15) K. From the determined densities, the apparent molar volumes, the cubic expansion coefficients and the second derivatives of volume with respect to temperature which are interrelated with the derivatives of isobaric heat capacities with respect to pressure were evaluated. These derivatives were qualitatively correlated with the changes in the structure of water when itaconic acid is dissolved in it.     

Excess enthalpy,density, and heat capacity for binary systems of alkylimidazolium-based ionic liquids + water

Experimental measurements of excess molar enthalpy, density, and isobaric molar heat capacity are presented for a set of binary systems ionic liquid + water as a function of temperature at atmospheric pressure. The studied ionic liquids are 1-butyl-3-methylpyridinium tetrafluoroborate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-butyl-3-methylimidazolium methylsulfate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate. Excess molar enthalpy was measured at 303.15 K whereas density and heat capacity were determined within the temperature range (293.15 to 318.15) K. From experimental data, excess molar volume and excess molar isobaric heat capacity were calculated. The analysis of the excess properties reveals important differences between the studied ionic liquids which can be ascribed to their capability to form hydrogen bonds with water molecules.     

PVT,viscosity, and surface tension of ethanol: New measurements and literature data evaluation

In this work, the results of density, viscosity, and surface tension measurements for ethanol are presented. Ethanol with stated mass fraction purity greater than 0.998 was further purified using molecular sieves. Density was measured within the temperature and pressure ranges, respectively, T = (278.15 to 353.15) K and p = (0.1 to 35) MPa by means of a vibrating tube densimeter, model DMA 512P from Anton Paar with an estimated uncertainty of ±0.5 kg · m^?3. The experimental (p, ρ, T) results have been correlated by Tait equation. From this equation the isobaric expansivity, the isothermal compressibility, and the thermal pressure coefficient have been calculated. Viscosity was measured over the range T = (273.15 to 346.15) K using an Ubbelohde viscometer with a Schott–Geräte automatic measuring unit (Model AVS-470) with the associated uncertainty of ±0.001 mPa · s. The measured values were combined with selected values from the literature covering the range T = (223 K to 503) K, and the VTF model has been fitted to all the data. The surface tension of the liquid was measured using a tensiometer KSV Sigma 70 with a Du-Noüy ring for the range of T = (274.77 to 318.99) K with an uncertainty of ±0.01 mN · m^?1. Using these data and critically assessed data of other authors compiled from the literature, a form of the IAPWS equation was used to correlate the surface tension within the temperature range 223 K up to the critical temperature.     

Compressed liquid density measurements of dimethyl ether with a vibrating tube densimeter

A measurement system for compressed liquid densities over the temperature range of (293 to 373) K with pressures up to 70 MPa has been developed in this work. The core component of the system is a commercial vibrating tube densimeter (DMA-HPM) and the system was calibrated by water and vacuum via the method of Lagourette et al. Compressed liquid densities of dimethyl ether have been measured along nine isotherms between (293.84 and 372.94) K up to 70 MPa with the densimeter system as a function of temperature and pressure. The experimental data obtained in this work were correlated to the Tait equation with an average absolute percentage deviation of 0.014%. Also, the Tait equation was compared with the literature data.     

Thermodynamic and transport properties of (1-Butanol + 1,4-Butanediol) at temperatures from (298.15 to 318.15) K

Densities and kinematic viscosities have been measured for (1-butanol + 1,4-butanediol) over the temperature range from (298.15 to 318.15) K. The speeds of sound within the temperature range from (293.15 to 318.15) K have been measured as well. Using these results and literature values of isobaric heat capacities, the molar volumes, isentropic and isothermal compressibility coefficients, molar isentropic and isothermal compressibilities, isochoric heat capacities as well as internal pressures were calculated. Also the corresponding excess and deviation values (excess molar volumes, excess isentropic and isothermal compressibility coefficients, excess molar isentropic and isothermal compressibilities, different defined deviation speed of sound and dynamic viscosity deviations) were calculated. The excess values are negative over the whole concentration and temperature range. The excess and deviation values are expressed by Redlich–Kister polynomials and discussed in terms of the variations of the structure of the system caused by the participation of the two different alcohol molecules in the dynamic intermolecular association process through hydrogen bonding at various temperatures. The predictive abilities of Grunberg–Nissan and McAllister equations for viscosities of mixtures have also been examined.     

Temperature and pressure dependences of volumetric properties of two poly(propylene glycol) dimethyl ether lubricants

The densities at high pressures of two dimethoxy end-capped poly(propylene glycols), CH₃–O–[CH₂–CH(CH₃)–O]_m–CH₃, with average molar masses higher than 1300 g · mol^?1, were measured in the range (0.1 to 60) MPa at five different temperatures from (298.15 to 398.15) K. The measurements were performed in a high-pressure vibrating tube densimeter. A correction factor, due to the viscosity of the sample, was applied to the experimental density values. The pressure–volume–temperature behavior of these lubricants was evaluated accurately over wide temperature and pressure ranges and correlated successfully with the empirical Tammann–Tait equation. The experimental data and the correlations were used to study the behavior and the influence of temperature and pressure on the isothermal compressibility, the isobaric thermal expansivity, and the internal pressure, as well as the effect of the polyether molecular structure on these properties.     

Heat capacities of the mixtures of ionic liquids with methanol at temperatures from 283.15 K to 323.15 K

The molar isobaric heat capacities of (methanol + 1-hexyl-3-methylimidazolium tetrafluoroborate) and (methanol + 1-methyl-3-octylimidazolium tetrafluoroborate) mixtures have been determined over the temperature range from 283.15 K to 323.15 K within the whole composition range. The excess molar heat capacities of investigated mixtures have been fitted to the Redlich–Kister equation at several selected temperatures. Positive deviations from the additivity of molar heat capacities have been observed in both examined systems. The results obtained have been discussed in terms of molecular interactions in binary mixtures.     

PρT measurements and derived properties of liquid 1-alkanols

The density of compressed liquid (C2 to C11) 1-alkanols was measured with a vibration tube densimeter over the temperature range from (278.15 to 358.15) K and pressures up to 60 MPa, with an uncertainty of ±0.0012 g · cm⁻³. Density values were correlated with pressure and temperature by the TRIDEN 10-parameter equation. Isothermal compressibility, isobaric thermal expansivity and internal pressure were calculated from the experimental results. The influence of the carbon-chain lengths over the thermophysical properties obtained was studied.