Showing papers in "Journal of Physical and Chemical Reference Data in 2017"

Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds and Ionic Liquids. Sublimation, Vaporization, and Fusion Enthalpies from 1880 to 2015. Part 2. C11–C192

Abstract: The second part of this compendium concludes with a collection of phase change enthalpies of organic molecules inclusive of C11–C192 reported over the period 1880–2015. Also included are phase change enthalpies including fusion, vaporization, and sublimation enthalpies for organometallic, ionic liquids, and a few inorganic compounds. Paper I of this compendium, published separately, includes organic compounds from C1 to C10 and describes a group additivity method for evaluating solid, liquid, and gas phase heat capacities as well as temperature adjustments of phase changes. Paper II of this compendium also includes an updated version of a group additivity method for evaluating total phase change entropies which together with the fusion temperature can be useful in estimating total phase change enthalpies. Other uses include application in identifying potential substances that either form liquid or plastic crystals or exhibit additional phase changes such as undetected solid–solid transitions or behave ani...

Reference Correlation for the Viscosity of Carbon Dioxide.

Abstract: A comprehensive database of experimental and computed data for the viscosity of carbon dioxide (CO2) was compiled and a new reference correlation was developed. Literature results based on an ab initio potential energy surface were the foundation of the correlation of the viscosity in the limit of zero density in the temperature range from 100 to 2000 K. Guided symbolic regression was employed to obtain a new functional form that extrapolates correctly to 0 and to 10 000 K. Coordinated measurements at low density made it possible to implement the temperature dependence of the Rainwater-Friend theory in the linear-in-density viscosity term. The residual viscosity could be formulated with a scaling term ργ/T, the significance of which was confirmed by symbolic regression. The final viscosity correlation covers temperatures from 100 to 2000 K for gaseous CO2 and from 220 to 700 K with pressures along the melting line up to 8000 MPa for compressed and supercritical liquid states. The data representation is mo...

Positron Scattering from Molecules: An Experimental Cross Section Compilation for Positron Transport Studies and Benchmarking Theory

Abstract: We present a compilation of recommended positron–molecule cross sections for a range of scattering processes including elastic scattering, vibrational excitation, discrete electronic-state excitation, positronium formation, ionization, and also for the grand total cross section. Where possible, in particular for possible application in positron transport simulations for a given molecule, we try and list data for energies in the range 0.1–1000 eV although in practice the actual energy is highly target–molecule and scattering process specific. Aside from being relevant to positron transport studies, through, for example, Monte Carlo simulations, the present compilation should also be germane for benchmarking the validity and accuracy of positron–molecule scattering calculations and, just as importantly, to allow a comparison with corresponding electron scattering results. That latter comparison can shed real light on the projectile–target interactions that underpin the scattering dynamics.

Estimation of Solvation Quantities from Experimental Thermodynamic Data: Development of the Comprehensive CompSol Databank for Pure and Mixed Solutes

Abstract: The Gibbs energy of solvation measures the affinity of a solute for its solvent and is thus a key property for the selection of an appropriate solvent for a chemical synthesis or a separation process. More fundamentally, Gibbs energies of solvation are choice data for developing and benchmarking molecular models predicting solvation effects. The Comprehensive Solvation-CompSol-database was developed with the ambition to propose very large sets of new experimental solvation chemical-potential, solvation entropy, and solvation enthalpy data of pure and mixed components, covering extended temperature ranges. For mixed compounds, the solvation quantities were generated in infinite-dilution conditions by combining experimental values of pure-component and binary-mixture thermodynamic properties. Three types of binary-mixture properties were considered: partition coefficients, activity coefficients at infinite dilution, and Henry's-law constants. A rigorous methodology was implemented with the aim to select data at appropriate conditions of temperature, pressure, and concentration for the estimation of solvation data. Finally, our comprehensive CompSol database contains 21 671 data associated with 1969 pure species and 70 062 data associated with 14 102 binary mixtures (including 760 solvation data related to the ionic-liquid class of solvents). On the basis of the very large amount of experimental data contained in the CompSol database , it is finally discussed how solvation energies are influenced by hydrogen-bonding association effects.

Correlations for the Viscosity and Thermal Conductivity of Ethyl Fluoride (R161).

Abstract: This paper presents new wide-ranging correlations for the viscosity and thermal conductivity of ethyl fluoride (R161) based on critically evaluated experimental data The correlations are designed to be used with a recently published equation of state that is valid from 130 to 450 K, at pressures up to 100 MPa The estimated uncertainty at a 95% confidence level is 2% for the viscosity of low-density gas (pressures below 05 MPa) and 3% for the viscosity of the liquid over the temperature range from 243 to 363 K at pressures up to 30 MPa The estimated uncertainty is 3% for the thermal conductivity of the low-density gas and 3% for the liquid over the temperature range from 234 to 374 K at pressures up to 20 MPa Both correlations may be used over the full range of the equation of state, but the uncertainties will be larger, especially in the critical region

Reference Correlations for the Viscosity and Thermal Conductivity of n-Undecane

Abstract: This paper presents new, wide-ranging correlations for the viscosity and thermal conductivity of n-undecane based on critically evaluated experimental data. The correlations are designed to be used with a recently published equation of state that is valid from the triple point to 700 K, at pressures up to 500 MPa, with densities below 776.86 kg m−3. The estimated uncertainty for the dilute-gas viscosity is 2.4%, and the estimated uncertainty for viscosity in the liquid phase for pressures up to 60 MPa over the temperature range 260 K–520 K is 5%. The estimated uncertainty is 3% for the thermal conductivity of the low-density gas and 3% for the liquid over the temperature range from 284 K to 677 K at pressures up to 400 MPa. Both correlations behave in a physically reasonable manner when extrapolated to the full range of the equation of state, but care should be taken when using the correlations outside of the validated range. The uncertainties will be larger outside of the validated range and also in the ...

Cross Sections for Electron Collisions with Acetylene

Abstract: Cross section data are compiled from the literature for electron collisions with the acetylene (HCCH) molecule. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. The data derived from swarm experiments are also considered. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed through early 2016.

IUPAC-NIST Solubility Data Series. 104. Lithium Sulfate and its Double Salts in Aqueous Solutions

Abstract: The solubility data for lithium sulfate and its double salts in water are reviewed. Where appropriate, binary, ternary, and multicomponent systems are critically evaluated. The best values were selected on basis of these evaluations and presented in tabular form. Fitting equations and plots are provided. The quantities, units, and symbols used are in accord with IUPAC recommendations. The original data have been reported and, if necessary, transferred into the units and symbols recommended by IUPAC. The literature on solubility data is covered up to the end of 2015.

Recommended Ideal-Gas Thermochemical Functions for Heavy Water and its Substituent Isotopologues

Abstract: Accurate temperature-dependent ideal-gas internal partition functions, Qint(T), and several derived thermochemical functions are reported for heavy water, with an oxygen content corresponding to the isotopic composition of Vienna Standard Mean Ocean Water (VSMOW), and its constituent isotopologues, D216O, D217O, and D218O, for temperatures between 0 and 6000 K. The nuclear-spin-dependent partition functions are obtained by the direct summation technique, involving altogether about 16 000 measured and more than nine million computed bound rovibrational energy levels for the three molecules. Reliable standard uncertainties, as a function of temperature, are estimated for each thermochemical quantity determined, including the enthalpy, the entropy, and the isobaric heat capacity of the individual nuclear-spin-equilibrated isotopologues and of heavy water. The accuracy of the heavy-water ideal-gas Cp(T) is unprecedented, below 0.01% up to 1800 K. All the thermochemical functions are reported, in 1 K increment...

Reference Correlations for the Thermal Conductivity of Liquid Bismuth, Cobalt, Germanium and Silicon.

Abstract: The available experimental data for the thermal conductivity of liquid bismuth, cobalt, germanium and silicon have been critically examined with the intention of establishing thermal conductivity reference correlations. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the thermal conductivity of liquid bismuth, cobalt, germanium, and silicon are respectively characterized by uncertainties of 10, 15, 16 and 9.5% at the 95% confidence level.

Critical Evaluation of Thermodynamic Properties for Halobenzoic Acids Through Consistency Analyses for Results from Experiment and Computational Chemistry

Abstract: Thermodynamic properties of the twelve monohalobenzoic acids are critically evaluated through the application of computational chemistry methods for the ideal-gas phase and thermodynamic consistency assessment of properties determined experimentally and reported in the literature, including enthalpies of combustion, enthalpies of sublimation, and enthalpies of fusion. The compounds of interest are the 2-, 3-, and 4-halo isomers of fluoro-, chloro-, bromo-, and iodobenzoic acids. Computations were validated by comparison with critically evaluated entropies and heat capacities in the ideal-gas state for benzoic acid, benzene, and some halobenzenes. Experimental enthalpies of formation for 2- and 3-bromobenzoic acids, measured by well-established research groups, are mutually inconsistent and further, are shown to be inconsistent with the computations and assessment in this work. Origins of the discrepancies are unknown, and recommended values for these compounds are based on computations and enthalpies of s...

Reference Correlation of the Thermal Conductivity of Cyclohexane from the Triple Point to 640 K and up to 175 MPa

Abstract: New, wide-range reference equations for the thermal conductivity of cyclohexane as a function of temperature and density are presented. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. We estimate the uncertainty (at the 95% confidence level) for the thermal conductivity of cyclohexane from the triple point (279.86 K) to 650 K at pressures up to 175 MPa to be 4% for the compressed liquid and supercritical phases. For the low-pressure gas phase (up to 0.1 MPa) over the temperature range 280–680 K, the estimated uncertainty is 2.5%. Uncertainties in the critical region are much larger, since the thermal conductivity approaches infinity at the critical point and is very sensitive to small changes in density.

Cross Sections for Electron Collisions with Ammonia

Abstract: Cross-sectional data are surveyed for electron collisions with ammonia. Collision processes considered are total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, ionization, and dissociative electron attachment. After a review of the literature (up to March 2017), recommended values of the cross section are determined, as far as possible.

Cross Sections for Electron Collisions with NF3

Abstract: Cross section data are compiled from the literature for electron collisions with nitrogen trifluoride (NF3) molecules. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed until end of 2016.

Lanthanide Ionization Energies and the Sub-Shell Break. Part 2. The Third and Fourth Ionization Energies

Abstract: By interpolating a 4fq6s → 4fq7s transition within the sequence f1 → f14 rather than between f0 and f14, revised third and fourth ionization energies of the lanthanides have been obtained. The revised values, together with the second ionization energies calculated in a previous paper, are used to calculate values of the standard enthalpies of formation of the gaseous tripositive ions, ΔfHƟ(M3+,g), and of the lattice and hydration enthalpies of some lanthanide compounds and ions in the trivalent and tetravalent states. The displacements of f0 values from nearly smooth f1 → f14 variations exceed 30 kJ mol−1 and indicate substantial subshell breaks.

Lanthanide Ionization Energies and the Sub-Shell Break. Part 1. The Second Ionization Energies

Abstract: By interpolating a 4fq6s → 4fq7s transition within the sequence f1 → f14 rather than between f0 and f14, revised second ionization energies of the lanthanides have been obtained. In the early part of the series, between cerium and samarium, the revisions are significantly higher than currently accepted values. The revised values have been used to calculate the energy variation for the conversion of Ln(g, 4fq6s2) to Ln2+(g, 4fq) across the series Ba → Yb. The variation is smooth between lanthanum and ytterbium but the barium point at q = 0 is displaced downwards by more than 0.3 eV, thereby representing a significant sub-shell break. A case is also made for a substantial change to the second ionization energy of lutetium, the revised value being 14.13 ± 0.10 eV.

On the Melting Curve of Sulfur Hexafluoride

Abstract: A previous correlation for the melting curve of sulfur hexafluoride (SF6) is inconsistent with the thermodynamic slope at the triple point derived from the Clapeyron equation. It is shown that this is probably due to the previous authors combining an accurate measurement of the triple point with melting-curve data that were distorted by impurities. A new equation is proposed that is consistent with the Clapeyron slope.

Electron Collisions with Hydrogen Fluoride

Abstract: Cross section data are reviewed for electron collisions with hydrogen fluoride. Collision processes considered are total scattering, elastic scattering, excitations of rotational, vibrational, and electronic states, ionization, and dissociative electron attachment. After a survey of the literature, recommended values of the cross sections are determined, as far as possible.