Index of content:
Volume 32, Issue 4, December 2003
32(2003); http://dx.doi.org/10.1063/1.1539857View Description Hide Description
Tables of critically compiled wavelengths, energy levels, line classifications, and transition probabilities are given for spectra of ionized sulfur (S VIII–S XIV) in the region 21–170 Å. These tables provide data of interest for the Emission Line Project in support of the analysis of astronomical data from the Chandra X-RayObservatory. They will also be useful for the diagnostics of plasmas encountered in fusion energy research. The transition probabilities were obtained mainly from recent sophisticated calculations carried out with complex computer codes.
32(2003); http://dx.doi.org/10.1063/1.1555590View Description Hide Description
Condensationnucleationlight scatteringdetection in principle works by converting the effluent of the chromatographic separation into an aerosol and then selectively evaporating the mobile phase, leaving less volatile analytes and nonvolatile impurities as dry aerosol particles. The dry particles produced are then exposed to an environment that is saturated with the vapors of an organic solvent (commonly n-butanol). The blend of aerosol particles and organic vapor is then cooled so that conditions of vapor supersaturation are achieved. In principle, the vapor then condenses onto the dry particles, growing each particle (ideally) from as small as a few nanometers in diameter into a droplet with a diameter up to about 10 μm. The grown droplets are then passed through a beam of light, and the light scattered by the droplets is detected and used as the detector response. This growth and detection step is generally carried out using commercial continuous-flow condensation nucleus counters. In the present research, the possibility of using other fluids than the commonly used n-butanol is investigated. The Kelvin equation and the Nucleation theorem [Anisimov et al. (1978)] are used to evaluate a range of fluids for efficacy of growing small particles by condensationnucleation. Using the available experimental data on vapor nucleation, the correlations of Kelvin diameters (the critical embryo sizes) and the bulk surface tension with dielectric constants of working liquids are found. A simple method for choosing the most efficient fluid, within a class of fluids, for growth of small particles is suggested.
32(2003); http://dx.doi.org/10.1063/1.1556431View Description Hide Description
This work deals with the critical temperature for saturated and unsaturated aliphatic hydrocarbons. For 175 hydrocarbons (branched alkanes, branched and unbranched alkenes, and alkynes), an existing lack of critical temperature values have been complemented. Prediction methods have been used, the usefulness of which for specific groups and subgroups of the above mentioned hydrocarbons had been previously critically evaluated. The evaluation of accuracy of the relevant aspects of these methods is given in this study. An additional result of this work is the creation of a set of recommended experimental data on critical temperatures and normal boiling points for aliphatic hydrocarbons. Such a set has been created mainly for the purpose of evaluation of prediction methods applied in this study.
32(2003); http://dx.doi.org/10.1063/1.1557529View Description Hide Description
The recommended vapor–liquid equilibrium (VLE) data for 36 binary systems involving primary, secondary, and tertiary alcohols with n-alkanes and isoalkanes [with the exception of 1-alkanols–n-alkane systems, which were presented in Part 1 of this series—J. Phys. Chem. Ref. Data 31(3), 702 (2002)] have been obtained after critical evaluation of all data (744 data sets) reported in the open literature up to the middle of 2002. The evaluation procedure consisted in combining the thermodynamic consistency tests, data correlation, comparison with enthalpy of mixing data, and comparison of VLE data for various mixtures. The data were correlated with equations based on local compositions concept as well as with equation of state appended with chemical term (EoSC) proposed by Góral. The recommended data are presented in the form of sheets containing tables of data, figures and auxiliary information. Each sheet corresponds to one system and contains three isotherms (spaced by at least 15 K) and one isobar (preferably at 101.32 kPa). Experimental gaps were completed with the predicted data.
32(2003); http://dx.doi.org/10.1063/1.1559671View Description Hide Description
A new formulation for the thermodynamic properties of trifluoromethane (R-23) is presented. The formulation is valid for single-phase and saturation states for temperatures from the triple point (118.02 K) to 475 K, pressures up to 120 MPa, and densities up to 24.31 The formulation includes a fundamental equation and ancillary functions for the estimation of saturation properties. The experimental data used to determine the fundamental equation included pressure–density–temperature isobaric heat capacity isochoric heat capacity saturation heat capacityspeed of sound and vapor pressure. A nonlinear regression algorithm was used to determine the constants and exponents of various functions within the formulation. Experimental data and values computed using the formulation are compared to verify the uncertainties in the calculated properties. The formulation presented may be used to compute densities to within ±0.1%, heat capacities to within ±0.5%, speed of sound to within ±0.5%, and vapor pressures to within ±0.2%, except near the critical point.
Ultrasonic Parameters as a Function of Absolute Hydrostatic Pressure. I. A Review of the Data for Organic Liquids32(2003); http://dx.doi.org/10.1063/1.1555588View Description Hide Description
This review provides an overview of experimental results involving ultrasonic parameters as a function of absolute hydrostaticpressure in organic liquids. Major topics of discussion include the pioneering work of Litovitz and Carnevale involving deduction of the chemical and structural properties of liquids from acoustical properties as a function of pressure; modern general ultrasonic studies of a broad range of organic liquids; work accomplished by Russians and others from the former Soviet block countries, particularly the work headed by Otpuschennikov at the Kursk Pedagogical Institute; the studies involving refrigerants published by Takagi at the Kyoto Institute of Technology; tribological and petroleum industry studies related to oils; Brillouin scattering experiments; and thermodynamic methods of measurement. The importance of ultrasonic parameters as a function of pressure to the understanding of a variety of processes is highlighted. A table of 325 liquids and liquid mixtures with a total of 366 entries indexed by chemical name is provided. Publications involving a specific liquid are cited within the table under the entry for that liquid, with the author’s name, aim of the study (e.g., speed of sound or absorption studies), methodology, and pressure/temperature ranges of the experimentation also given (197 references).
Ultrasonic Parameters as a Function of Absolute Hydrostatic Pressure. II. Mathematical Models of the Speed of Sound in Organic Liquids32(2003); http://dx.doi.org/10.1063/1.1555589View Description Hide Description
Polynomial expressions for the speed of sound as a function of pressure for 68 different organic liquids are presented in tabular form. (The liquids form a subset of those discussed in the companion paper: Ultrasonic parameters as a function of absolute hydrostaticpressure. I. A review of the data for organic liquids.) The polynomial expressions are based upon the experimental results reported by many different researchers. For some common liquids, such as benzene, hexane, ethanol, and carbon tetrachloride, the results of as many as five different researchers are reported. These results sometimes vary widely—far more than would be expected from calculated experimental uncertainties. An analysis is presented of how well pressure-dependent polynomials fit the experimental data when the number of coefficients is increased. The error in the polynomial fit is also explored when both pressure and temperature dependencies are present. Finally, differences between ultrasonic and Brillouin scattering experimental results are discussed.
A Comprehensive and Critical Compilation, Evaluation, and Selection of Physical–Chemical Property Data for Selected Polychlorinated Biphenyls32(2003); http://dx.doi.org/10.1063/1.1562632View Description Hide Description
Accurate physical–chemical properties (aqueous solubility octanol–water partition coefficient vapor pressureP, Henry’s law constant H, octanol–air partition coefficient octanol solubility are of fundamental importance for modeling the transport and fate of organic pollutants in the environment. Energies of phase transfer are used to describe the temperature dependence of these properties. When trying to quantify the behavior of contaminant mixtures such as the polychlorinated biphenyls, consistent physical–chemical properties are required for each individual congener. A complete set of temperature dependent property data for sixteen polychlorinated biphenyls (PCB-3, 8, 15, 28, 29, 31, 52, 61, 101, 105, 118, 138, 153, 155, 180, 194) was derived, based on all experimentally obtained values reported for these congeners in the literature. Log mean values derived from the experimental data were adjusted to yield an internally consistent set of data for each congener. These adjusted data also show a greater degree of interhomologue consistency, which can be illustrated with the help of simple quantitative structure-property relationships that use molar mass and the number of chlorine substitutions in ortho-positions as descriptors. The extent of the required adjustment gives an indication of the uncertainty of the averaged measured values and is typically lower than might be expected from the range of the reported measured values.
Viscosity and pVT–Second Virial Coefficient of Binary Noble–Globular Gas and Globular–Globular Gas Mixtures Calculated by Means of an Isotropic Temperature-Dependent Potential32(2003); http://dx.doi.org/10.1063/1.1562633View Description Hide Description
This work presents results of an extension of our earlier studies of the transport and equilibrium properties of pure heavy globular gases. It demonstrates a simple and reliable procedure for estimating the equilibrium and transport properties of their mixtures using the pure gas potentials of interaction when there are no available experimental data. Here we consider binary gas mixtures of globular gases between themselves and with the noble gases as well. The gases involved are: Ar, Kr, and Xe. The calculations were performed by means of the so called isotropic temperature–dependent potential (ITDP) introduced by us earlier and applied to some binary mixtures The and noble gases potentials of interactions have been determined in a Lennard-Jones shape in the temperature range 200–1000 K by fitting a large number of viscosity and pVT–second virial coefficient data measured by different authors with different experimental techniques. The ITDP parameters of molecular gases were taken from the tables we have determined and published earlier [L. Zarkova and U. Hohm, J. Phys. Chem. Ref. Data 31, 183 (2002)]. Simple combination rules allow us to take into account the influence of the temperature on the thermophysical properties of the binary gas mixtures containing heavy globular molecules. Tables with potential parameters of equal and unequal particles and properties of the equimolar mixtures are given for all mixtures in the temperature range 200–900 (1000) K. The deviations between experimental and calculated viscosity and second virial coefficient data of some more examined mixtures permit to evaluate the quality of the proposed approach.
32(2003); http://dx.doi.org/10.1063/1.1565352View Description Hide Description
A simple general corresponding-states principle has been developed to represent the vapor pressure of tritium oxide from its triple point to its critical point, to describe the available experimental data, and to extrapolate beyond their range. This work takes advantage of the adoptions of the ITS-90 temperature scale and of the new critical parameters obtained from the extended corresponding-states principle. The vapor pressure data are described within their scatter in the entire temperature range. Comparisons with the available experimental data show that the extended corresponding-states principle for vapor pressure can calculate values with good accuracy. The substance-dependent characteristic parameters are given, such as critical temperature, critical density, critical pressure, and acentric factor. The values of the pressures, along with their first and second derivatives, as a function of temperature over the entire region from the triple point to the critical point are tabulated and recommended for scientific and practical uses.
Thermochemical Properties, and of 1,4-Dioxin, 2,3-Benzodioxin, Furan, 2,3-Benzofuran, and Twelve Monochloro and Dichloro Dibenzo-p-dioxins and Dibenzofurans32(2003); http://dx.doi.org/10.1063/1.1571057View Description Hide Description
Values for and are computed by density functional B3LYP/6-31G(d,p) and calculation methods for 12 monochloro and dichloro dibenzo-p-dioxins and dibenzofurans: 1-chloro dibenzo-p-dioxin, 2-chloro dibenzo-p-dioxin, 1,6-dichloro dibenzo-p-dioxin, 1,8-dichloro dibenzo-p-dioxin, 1,9-dichloro dibenzo-p-dioxin, 2,8-dichloro dibenzo-p-dioxin, 3-chloro dibenzofuran, 4-chloro dibenzofuran, 1,6-dichloro dibenzofuran, 3,6-dichloro dibenzofuran, 3,7-dichloro dibenzofuran, and 4,6-dichloro dibenzofuran. Molecular structures and vibration frequencies are determined at the B3LYP/6-31G(d,p) level of theory. Isodesmic reactions are utilized at each calculation level to determine the enthalpy of formation of each species. Contributions to the entropy and the heat capacity from translation, vibration, and external rotations are calculated using the rigid-rotor-harmonic-oscillator approximation based on the B3LYP/6-31G(d,p) structures. The enthalpies of formation for 1,4-dioxin, furan, 2,3-benzodioxin, 2,3-benzofuran, dibenzo-p-dioxin, and dibenzofuran are also calculated. Thermochemical properties of two composite central atom groups and four interaction groups are derived for use in a group additivity scheme to calculate these thermochemical properties of polychlorinated dibenzo-p-dioxins and dibenzofurans.