Volumetric properties of mixtures of fluoroalcohols and water at high pressures

Densities of aqueous solutions of 2,2,2-trifluoroethanol, 2,2,3,3-tetranuoropropanol, and 2,2,3,3,3-pentanuoropropanol have been measured with a vibrating-tube densitometer. Measurements were performed at temperatures of 298 and 323 K and at pressures up to 80 MPa with an estimated uncertainty of ±0.2 %. Molar volumes obtained for these mixtures are correlated with pressure by the Tait equation within the experimental uncertainty. Excess molar volume, isothermal compressibility, and partial molar volume of these mixtures are determined in terms of this correlation equation and compared with those of the aqueous solutions of hydrocarbon alcohols. Composition dependence of partial molar volume is discussed in comparison with that of Raman spectroscopic data.     

Ultrasonic Velocity and Density Studies of Solutions of Maleic Acid and Tartaric Acid in Water at <Emphasis Type="Italic">T</Emphasis> = (298.15 and 308.15) K

Ultrasonic-velocity and density measurements of aqueous solutions of maleic acid and tartaric acid have been made as a function of molality, at T = (298.15 and 308.15) K, and at atmospheric pressure. A molality range has been studied from (0.2603 to 2.6309) mol·kg⁻¹ and (0.4451 to 2.6621) mol·kg⁻¹ for maleic and tartaric acids, respectively. The experimental data have been correlated with molality using a polynomial equation. Furthermore, apparent molar volume, partial molar volume, apparent-specific molar volume, isentropic compressibility, apparent molar isentropic compressibility, limiting apparent molar isentropic compressibility, and isentropic apparent-specific compressibility values have been calculated from experimental values of densities and ultrasonic velocities. The calculated parameters have been interpreted in terms of solute–solvent interactions, solute–solute interactions, structure making/breaking behavior of acids, and their taste quality in water.     

PVTx and Isochoric Heat Capacity Measurements for Aqueous Methanol Solutions

Isochoric heat capacity and PVTx properties of an aqueous methanol solution (0.50 mass fraction or 0.36 mole fraction of methanol) were measured in the liquid phase with a twin-cell adiabatic calorimeter. Temperatures ranged from 333 to 422 K, and pressures ranged to 20 MPa. The calorimetric cell (70 cm³ capacity) was surrounded by adiabatic thermal shielding (high vacuum) and a steel-sheathed electric heater wound tightly on its surface. By combining the various sources of experimental uncertainty using a root-sum-of-squares formula, the relative uncertainty of C _V is estimated to be 2%. The uncertainties of the density, temperature (absolute), and pressure measurements are, respectively, about 0.1%, 40 mK, and ±7 kPa. The measured densities were used to calculate excess molar volumes that were compared with values calculated with a reliable model by Simonson et al. Good agreement within ±0.008 cm³mol^–1 (or ±0.03% of the density) was found between measured values of excess molar volume and those calculated from the model. Values of saturated liquid densities were determined by extrapolating experimental P-T data to the saturation curve.     

Synthesis of 1,3-Dimethylimidazolium Chloride and Volumetric Property Investigations of Its Aqueous Solution

By investigating the vapor pressure of the solvent and the affinity between ionic liquids (ILs) and the solvent, it is proposed that 1,3-dimethylimidazolium chloride ([Mmim]Cl) has the potential to be used as a novel absorbent species with the absorption cycle working fluid. Adopting a high-pressure reaction kettle, the method of gas–liquid phase reaction was used to synthesize [Mmim]Cl under the conditions of 348.15 K and 0.7 MPa. The densities of [Mmim]Cl aqueous solutions were measured for mass fractions in the range from 20% to 90% at 293.15 K, 298.15 K, 303.15 K, 308.15 K, 313.15 K, and 318.15 K with a digital vibrating-tube densimeter. The excess volume, the apparent molar volume, the partial molar volume, and the apparent molar expansibility of this system were investigated, and the influences of variations of the cation and anion on the density of several IL aqueous solutions are discussed.     

PVTx Measurements and Partial Molar Volumes for Aqueous Li2SO4 Solutions at Temperatures from 297 to 573 K and at Pressures Up to 40 MPa

Densities of four aqueous Li₂SO₄ solutions (0.0944, 0.2798, 0.6115, 0.8850 molkg^–1) have been measured in the liquid phase with a constant-volume piezometer immersed in a precision liquid thermostat. Measurements were made for ten isotherms between 297 and 573 K. The range of pressure was from 3.9 to 40 MPa. The total uncertainty of density, pressure, temperature, and concentration measurements were estimated to be less than 0.06%, 0.05%, 10 mK, and 0.014%, respectively. The reliability and accuracy of the experimental method was confirmed with measurements on pure water for two isobars at 10 and 38 MPa. Experimental and calculated (IAPWS formulation) densities for pure water show excellent agreement within their experimental uncertainties (average absolute deviation within 0.02 to 0.05%). Saturated liquid densities were determined by extrapolating experimental P- data to the vapor pressure at fixed temperature and composition using an interpolating equation. Apparent and partial molar volumes were derived using measured densities for aqueous solutions and pure water. Derived apparent molar volumes were extrapolated to zero concentration to yield partial molar volumes of electrolyte (Li₂SO₄) at infinite dilution. The temperature, pressure, and concentration dependences of partial and apparent molar volumes were studied. A polynomial type of equation of state for specific volume was obtained as a function of temperature, pressure, and composition by a least-squares method using the experimental data. The average absolute deviation (AAD) between measured and calculated values from this polynomial equation for density was 0.02%. Measured values of solution density, and apparent and partial molar volumes were compared with data reported in the literature by other authors.     

Viscosity of twelve hydrocarbon liquids in the temperature range 298–348 K at pressures up to 110 MPa

New experimental data on the viscosity of 12 organic liquids are presented at temperatures of 25, 30, 50, and 75°C and at pressures up to 110 MPa. The liquids measured are five n-alkanes (C₆, C₇, C₈, C₁₀, C₁₂), cyclohexane, and six aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylenes). The measurements were performed using a torsionally vibrating crystal method on a relative basis with an uncertainty less than 2%. A linear relationship between fluidity and molar volume, which is predicted from the hard-sphere theory, fails at pressures above 50 MPa. The rough hard-sphere model proposed by Chandler provides a reasonable representation of the data for aromatic hydrocarbons, while for n-alkanes the agreement is not satisfactory because of an aspherical shape of molecules. The viscosity data can be correlated well with the molar volume by a free-volume expression and also can be represented as a function of pressure by a similar expression to the Tait equation.     

Thermal Conductivity of Aqueous Sugar Solutions under High Pressure

Molecular energy transport in aqueous sucrose and glucose solutions of different mass fractions and temperatures is investigated up to 400 MPa, using the transient hot-wire method. The results reveal an increasing thermal conductivity with increasing pressure and decreasing mass fraction of sugar. No significant differences between sucrose and glucose solutions were observed. Different empirical and semi-empirical relations from the literature are discussed to describe and elucidate the behavior of the solutions with pressure. The pressure-induced change of the thermal conductivity of sugar solutions is mainly caused by an increase of the thermal conductivity and the decrease of molar volume of the water fraction. A simple pressure adapted mass fraction model permits an estimation of the thermal conductivity of the investigated solutions within an uncertainty of about 3%. An erratum to this article can be found at     

Investigating the Properties of Aqueous Monoisopropanolamine Using Density Data from 283.15K to 353.15K

The published isothermal density data of aqueous monoisopropanolamine (MIPA) for different temperatures are converted into molar volumes as a function of composition. Tikhonov regularization is applied to obtain the derivatives of molar volume with respect to composition. These derivatives are used to compute the two partial molar volumes of the aqueous solution covering the entire composition range and for all the temperatures reported. A second application of Tikhonov regularization is then used to obtain the partial molar coefficients of the thermal expansion of the solution under constant pressure. This is followed by an examination of the second derivative of the partial molar volumes with respect to temperature over the entire composition range. The signs of these derivatives, for different compositions and temperatures, allow the change in the molecular interaction between MIPA and water in aqueous solution to be discussed.     

Thermal conductivity of carbon tetrachloride in the temperature range 310 to 364 K at pressures up to 0.22 GPa

The paper reports new measurements of the thermal conductivity of carbon tetrachloride in the temperature range 310 to 364 K at pressures up to 0.22 GPa. The experimental data have an estimated uncertainty to ±0.3%. The hard-sphere theory of transport in dense fluids is employed to formulate a correlation scheme for the thermal conductivity as a function of density. A single equation represents the dependence of the thermal conductivity on density for all isotherms, the isotherms being distinguished by a characteristic value of the molar volume. It is shown that earlier measurements of the viscosity and self-diffusion coefficient of carbon tetrachloride may be represented in a similar fashion using consistent values of the characteristic volume.     

Solid hydrogen: Ground-state energy,pressure, and compressibility

The ground-state energy, the pressure, and the compressibility of solid molecular hydrogen is calculated by means of a modified Brueckner theory. The Bethe-Goldstone equation is solved to give the reaction matrix or an effective interaction in coordinate space; the ground-state energies for normal hydrogen and deuterium are calculated. Also, the pressure and the compressibility is estimated from the dependence of the ground-state energy on density or molar volume. Both hcp and fcc structures are considered. Theoretical results for the ground-state energy per particle are –82 K for solid hydrogen at a molar volume of 22 cm³/mole and –135 K for solid deuterium at a molar volume of 19 cm³/mole. The corresponding experimental results are –92 and –138 K, respectively. We obtain zero pressure for solid hydrogen at a molar volume of 22.45 cm³/mole and for solid deuterium at a molar volume of 19.2 cm³/mole. The corresponding experimental results are 22.65 and 19.56 cm³/mole, respectively. Theoretical results for the compressibility at zero pressure are 5.3×10^–4 atm^–1 for solid hydrogen and 2.6×10^–4 atm^–1 for solid deuterium. The corresponding experimental results are 4.9×10^–4 and 3.0×10^–4 atm^–1, respectively. The agreement with experimental results is reasonably good since higher order cluster terms are not included in this first approximation.     

Solid helium. I. Ground-state energy and compressibility

The ground-state energy and the compressibility of solid helium is calculated by means of a modified Brueckner theory. The Bethe-Goldstone equation is solved to give the reaction matrix or the effective interaction in coordinate space, and the ground-state energy for the two helium isotopes³He and⁴He is calculated. Also, the compressibility is estimated from the dependence of the ground-state energy on density or molar volume. Both bcc and hcp structures are considered. The calculations are done for two different two-body potentials, an Yntema-Schneider potential given by Brueckner and Gammel, and a Frost-Musulin potential given by Bruch and McGee. Theoretical results for the ground-state energy per particle are 0.2 to 2.6 K for solid³He at a molar volume of 24 cm³/mole, and –2.4 to –5.9 K for solid⁴He at a molar volume of 20 cm³/mole. The corresponding experimental results are –1.0 and –5.6 K, respectively. Theoretical results for the compressibility are 0.0031–0.0042 atm^–1 for solid³He at a molar volume of 22 cm³/mole, and 0.0014–0.0022 atm^–1 for solid⁴He at a molar volume of 18 cm³/mole. The corresponding experimental results are 0.0032 and 0.0014 atm^–1, respectively. The agreement with experimental results is reasonably good since higher order cluster terms are not included in this first approximation.     

Solid helium. II. Exchange energy in solid3He

The problem of exchange energy in solid³He is investigated, and the exchange integral for bcc³He is calculated. Results are obtained from reaction-matrix elements calculated by means of a modified Brueckner theory developed earlier, and the calculations are repeated for several values of the molar volume and the parameter ² defining the unperturbed wave functions. The final results indicate an antiferromagnetic and strongly density-dependent exchange integral with the absolute value decreasing rapidly with increasing density or decreasing molar volume. The calculations are made for two different two-body potentials, an Yntema-Schneider potential given by Brueckner and Gammel, and a Frost-Musulin potential given by Bruch and McGee. Theoretical results for the exchange integral are approximately –0.13 to –0.16 mK at a molar volume of 22 cm³/mole, and –0.44 to –0.57 mK at a molar volume of 24 cm³/mole. The corresponding experimental results are approximately –0.135 and –0.655 mK, respectively, i.e., the difference is generally within a factor of 1.5. The agreement with experimental results is reasonably good since the theoretical value is given by a small difference between several large terms of opposite sign almost canceling each other, and the results are also very sensitive to the choice of the parameter value ² for each molar volume.     

An automated volumometer: Thermodynamic properties of 1,1-dichloro-2,2,2-trifluoroethane (R123) for temperatures of 278.15 to 338.15 K and pressures of 0.1 to 380 MPa

An automated bellows volumometer is described which is capable of obtaining p-V-T data in the form of volume ratios for pressures up to 380 MPa. Volume ratios for 1,1-dichloro-2,2,2-trifluoroethane (R123) have been measured for six temperatures in the range of 278.15 to 338.15 K in the liquid phase. The accuracy of the volume ratios is estimated to be ±0.05 to 0.1% for the experimental temperatures up to 298.15 K and better than ±0.15% for temperatures above the normal boiling point of R123 (300.15 K). They agree with the literature data (which do not extend beyond 4 MPa) within the experimental uncertainty of those results. Isothermal compressibilities, isobaric expansivities, internal pressures, and isobaric molar heat capacities have been evaluated from the volumetric data. The pressure dependence of isobaric molar heat capacities obtained from the data generally agree with the pressure dependence of experimentally measured literature values within the latter's accuracy of ±0.4%.     

PVT and derived thermodynamic properties for the glycine-water system at temperatures from 298 to 323 K and pressures up to 300 MPa

The specific volumes for the glycine-water system have been measured in the temperature range 298–323 K and at pressures up to 300 MPa, using a glass piezometer. The uncertainties in the specific volume are estimated to be less than 0.03%. The PVT relations are correlated by the Tait equation. Good agreement was found with correlations by the Tait equation using a simple extension similar to that proposed by Dymond and Malhotra. The isothermal compressibility and apparent molar volume of glycine are calculated by the Tait equation. The apparent molar volume of glycine increases with increasing pressure.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Viscosity of mixtures of fluoroalcohols and water at high pressures

Viscosities of aqueous solutions of 2,2,2,-trifluoroethanol, 2,2,3,3-tetrafluoropropanol and 2,2,3,3,3-pentafluoropropanol have been measured with a falling-body viscometer. Measurements were performed at temperatures from 298 to 323 K and at pressures up to 80 MPa with an estimated uncertainty of ±2%. Viscosities obtained for these mixtures are represented by a simple empirical equation within the experimental uncertainty. The composition dependence of the viscosity is compared with that for mixtures of hydrocarbon alcohols and water.Paper dedicated to Professor Joseph Kestin.     

Comparative Studies of the Mixing Effect on the Thermal Effusivity,Compressibility, and Molar Volume for Aqueous Solutions of Alcohols

Concentration dependences of the thermal effusivity, isentropic compressibility coefficient, and molar volume were investigated experimentally for aqueous solutions of ethanol, 1-propanol, and 2-propanol. The thermal effusivity was determined using a photoacoustic method. The excess molar volume was found from measured densities, while the isentropic compressibility coefficient was calculated based on density and ultrasound velocity measurements. It has been shown that the dependence of the effusivity on concentration, expressed in mass fraction units, is nonlinear in the case of all the alcohols used. Moreover, the location of extreme deviations from linearity for the thermal effusivity, Δe, agrees well with that of characteristic points for the isentropic compressibility coefficient, κ _S , and the excess molar volume, V_m^E{V_{\rm m}^{\rm E}}, as a function of the concentration.     

Densities and Excess,Apparent, and Partial Molar Volumes of Binary Mixtures of BMIMBF<Subscript>4</Subscript> + Ethanol as a Function of Temperature,Pressure, and Concentration

The densities of five BMIMBF₄ (1-butyl-3-methylimidazolium tetrafluoroborate) + ethanol binary mixtures with compositions of (0.0701, 0.3147, 0.5384, 0.7452, and 0.9152) mole fraction BMIMBF₄ and of pure BMIMBF₄ have been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from 298 K to 398 K and at pressures up to 40 MPa. The total uncertainty of density, temperature, pressure, and concentration measurements were estimated to be less than 0.1 kg · m⁻³, 15 mK, 5 kPa, and 10⁻⁴, respectively. The uncertainties reported in this article are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The measured densities were used to study derived volumetric properties such as excess, apparent, and partial molar volumes. It is shown that the values of excess molar volume for BMIMBF₄ + ethanol mixtures are negative at all measured temperatures and pressures over the whole concentration range. The effect of water content on the measured values of density is discussed. The volumetric (excess, apparent, and partial molar volumes) and structural (direct and total correlation integrals, cluster size) properties of dilute BMIMBF₄ + ethanol mixtures were studied in terms of the Krichevskii parameter. The measured densities were used to develop a Tait-type equation of state.     

Reference Correlation for the Viscosity of Liquid Toluene from 213 to 373 K at Pressures to 250 MPa

A correlation in terms of temperature and molar volume is recommended for the viscosity of liquid toluene as a reference for high-pressure viscosity measurements. The temperature range covered is from 213 to 373 K, and the pressure range from atmospheric up to 250 MPa. The standard deviation of the proposed correlation is 1.36%, and, within a 95% confidence limit, the error is 2.7%. It is estimated that for densities up to 920 kg·m^–3the uncertainty of the viscosity values generated by this correlation is about ±2%.     

Bulk Properties of the Aqueous Solutions of Barium Chloride

Experimental investigations of the density of the aqueous solutions of BaCl₂ at temperatures of 298–573 K and pressures up to 40 MPa have been carried out with the method of a constantvolume piezometer. The error of experimental data does not exceed 0.06%. The equation of state has been composed and the coefficients of thermal expansion and isothermal compressibility and the partial molar volumes of the electrolyte have been calculated on its basis.     

The role of growth parameters on structural,morphology and optical properties of sprayed ZnS thin films

ZnS thin films were prepared by spray pyrolysis technique using aqueous of zinc chloride and thiourea at molar ratio of 1:1, 1:2, and 2:1. The depositions were carried out on substrates heated from 400 to 520 °C The films were then annealed under sulphur atmosphere for 90 min at 450 and 550 °C. The crystallites exhibit preferential orientation along the [002]_α or [111]_β directions. The films were characterized by XRD and SEM. The structure and morphology of sprayed films are controlled by both, the substrate temperature and the precursors molar ratio in the solution. The values of optical bandgap have been determined from the absorption spectra.