Showing papers in "Journal of Physical and Chemical Reference Data in 1986"

Chemical Kinetic Data Base for Combustion Chemistry. Part I. Methane and Related Compounds

Abstract: This document contains evaluated data on the kinetics and thermodynamic properties of species that are of importance in methanepyrolysis and combustion. Specifically, the substances considered include H, H2, O, O2, OH, HO2, H2O2, H2O, CH4, C2H6, HCHO, CO2, CO, HCO, CH3, C2H5, C2H4, C2H3, C2H2, C2H, CH3CO, CH3O2, CH3O, singlet CH2, and triplet CH2. All possible reactions are considered. In arriving at recommended values, first preference is given to experimental measurements. Where data do not exist, a best possible estimate is given. In making extrapolations, extensive use is made RRKM calculations for the pressure dependence of unimolecular processes and the BEBO method for hydrogen transfer reactions. In the total absence of data, recourse is made to the principle of detailed balancing, thermokinetic estimates, or comparisons with analogous reactions. The temperature range covered is 300–2500 K and the density range 1×1016–1×1021 molecules/cm3. This data base forms a subset of the chemical kinetic data base for all combustion chemistry processes. Additions and revisions will be issued periodically.

Triplet-triplet absorption spectra of organic molecules in condensed phases

Abstract: We present a compilation of spectral parameters associated with triplet–triplet absorption of organic molecules in condensed media. The wavelengths of maximum absorbance and the corresponding extinction coefficients, where known, have been critically evaluated. Other data, for example, lifetimes, energies and energy transfer rates, relevant to the triplet states of these molecules are included by way of comments but have not been subjected to a similar scrutiny. Work in the gas phase has been omitted, as have theoretical studies. We provide an introduction to triplet state processes in solution and solids, developing the conceptual background and offering an historical perspective on the detection and measurement of triplet state absorption. Techniques employed to populate the triplet state are reviewed and the various approaches to the estimation of the extinction coefficient of triplet–triplet absorption are critically discussed. A statistical analysis of the available data is presented and recommendations for a hierarchical choice of extinction coefficients are made. Data collection is expected to be complete through the end of 1984. Compound name, molecular formula and author indexes are appended.

Thermochemical Data on Gas‐Phase Ion‐Molecule Association and Clustering Reactions

Abstract: A comprehensive tabulation of the standard enthalpy change, ΔH°, entropy change, ΔS°, and free energy change, ΔG°, for the formation of ion clusters from ion‐molecule association reactions is given. The experimental methods which are used to derive the data are briefly discussed. For some experiments, dissociation energies of ion clusters are reported and listed under the category of ΔH°. The relationship between ΔH° and dissociation energy is discussed in the text.

Cross Sections for Collisions of Electrons and Photons with Oxygen Molecules

Abstract: Data have been compiled on the cross sections for collisions of electrons and photons with oxygen molecules (O2). For electron collisions, the processes included are: total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, and attachment. Ionization and dissociation processes are considered for photon impact. Cross‐section data selected are presented graphically. Spectroscopic and other properties of the oxygen molecule are summarized for understanding of the collision processes. The literature was surveyed through August 1987, but some more recent data are included when available to the authors.

Thermodynamic Properties of Iron and Silicon

Abstract: This work reviews and discusses the data on the various thermodynamic properties of iron and silicon available through March 1984 These include heat capacity, enthalpy, enthalpies of transition and melting, vapor pressure, and enthalpy of vaporization The recommended values for heat capacity, enthalpy, entropy, and Gibbs energy function cover the temperature range from 1 to 3200 K for iron and 1 to 3600 K for silicon The recommended values for vapor pressure cover the temperature range from 29815 to 3200 K for iron and from 29815 to 3600 K for silicon These values are referred to temperatures based on the International Practical Temperature Scale of 1968 The energy units used are joules per mol (J mol−1) The uncertainties in the recommended values of the heat capacity range from ±15% to ±5%

A Critical Review of Aqueous Solubilities, Vapor Pressures, Henry’s Law Constants, and Octanol–Water Partition Coefficients of the Polychlorinated Biphenyls

Abstract: Relationships between the environmentally relevant physical chemical properties of the polychlorinated biphenyls, namely, aqueous solubility, vapor pressure, Henry’s law constant, and octanol–water partition coefficient are discussed. Reported experimental data are tabulated and critically reviewed. Recommended values are given for 42 of the 209 congeners; however, procedures are suggested for estimating the properties of the other congeners. Properties of mixtures are not treated.

Improved International Formulations for the Viscosity and Thermal Conductivity of Water Substance

Abstract: This paper describes improved international formulations for the viscosity and thermal conductivity of water substance recently adopted by the International Association for the Properties of Steam.

Thermodynamic Properties of Nitrogen from the Freezing Line to 2000 K at Pressures to 1000 MPa

Abstract: A new fundamental equation explicit in Helmholtz energy for thermodynamic properties of nitrogen from the freezing line to 2000 K at pressures to 1000 MPa is presented. New independent equations for the vapor pressure and for the saturated liquid and vapor densities as functions of temperature are also included. The fundamental equation was selected from a comprehensive function of 100 terms on the basis of a statistical analysis of the quality of the fit. The coefficients of the fundamental equation were determined by a weighted least‐squares fit to selected P‐ρ‐T data, saturated liquid, and saturated vapor density data to define the phase equilibrium criteria for coexistence, and velocity of sound data. The fundamental equation and the derivative functions for calculating internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp), and velocity of sound are included. Tables of thermodynamic properties of nitrogen are given for liquid and vapor states within the range of...

Forbidden Lines in ns2npk Ground Configurations and nsnp Excited Configurations of Beryllium through Molybdenum Atoms and Ions

Abstract: Observed and predicted wavelengths of magnetic dipole lines arising within ground configurations of the type ns2npk(n=2 and 3, k=1 to 5) are compiled. For n=2 the compilation includes the elements B through Kr, and for k=5 it extends to Mo. For n=3 Al through Mo are included. In addition the 2s2p excited configuration of the Be i isoelectronic sequence for Be through Kr and 3s3p of the Mg sequence for Mg through Mo are included. For each line we give a calculated value for the transition probability obtained mainly from the Dirac‐Fock method or from the use of scaled radial integrals. The calculated wavelengths are obtained from known energy levels or from levels derived from scaled radial integrals. A small group of electric quadrupole lines seen in astronomical sources are included. The list contains 1660 predicted wavelengths in the range 100 A to 25.9 mm and 406 observed wavelengths in the range 325 A to 609 μm.

Recommended Rest Frequencies for Observed Interstellar Molecular Microwave Transitions—1985 Revision

Abstract: Critically evaluated transition frequencies for the molecular transitions detected in interstellar and circumstellar clouds are presented. The tabulated transitions are recommended for reference in future astronomical observations in the microwave and millimeter wavelength regions. The transition frequencies have been selected through a critical examination and analysis of the laboratory spectral data obtained from the literature. The information tabulated includes the species identity, transition frequency, uncertainty, and quantum state labels. For convenience, representative line antenna temperatures are listed for a typical astronomical source for each transition, and the references are cited for the laboratory and astronomical literature that have been employed.

Standard Reference Data for the Thermal Conductivity of Liquids

Abstract: The available experimental liquid‐phase thermal conductivity data for water, toluene, and n‐heptane have been examined with the intention of establishing standard reference values along the saturation line. The quality of available data is such that for toluene and water new standard reference values can be proposed with confidence limits better than ±1.0% for most of the normal liquid range. For n‐heptane there are insufficient reliable experimental data for the system to be treated as a primary reference standard, so a lower quality correlation has been developed which yields a set of secondary reference data with confidence limits of ±1.5% for most of the normal liquid range.

Thermodynamic Properties of Key Organic Oxygen Compounds in the Carbon Range C1 to C4. Part 2. Ideal Gas Properties

Abstract: The ideal gas thermodynamic properties of forty‐four key organic oxygen compounds in the carbon range C1 to C4 have been calculated by a statistical mechanical technique. The properties determined are the heat capacity (C○p), entropy {S○(T)−S○(0)}, enthalpy {H○(T)−H○(0)}, and Gibbs energy function {G○(T)−H○(0)}/T. The calculations have been performed, in most cases, over the temperature range 0 to 1500 K and at 1 bar. The contributions to the thermodynamic properties of compounds having internal‐ or pseudo‐ rotations have been computed by employing a partition function formed by the summation of the internal rotational or pseudorotational energy level for each rotor in the given molecule. These energy levels have been calculated by solving the wave equation using appropriate barrier heights, rotational constants, and potential functions for the given rotations. The thermodynamic properties have been calculated using a rigid‐rotor and harmonic‐oscillator molecular model for each species. The sources of mol...

The Viscosity and Thermal Conductivity of Normal Hydrogen in the Limit of Zero Density

Abstract: This paper contains a new representation of the viscosity and thermal conductivity coefficients of normal hydrogen in the limit of zero density as a function of temperature. The correlation is based upon the semiclassical kinetic theory of polyatomic gases and a body of critically evaluated experimental data. In the temperature range 200–400 K the accuracy of the representation of the viscosity is estimated to be ±0.5%. However, at the lowest temperature of 20 K and the highest temperature of 2200 K, the uncertainty rises to ±2.0%. The available thermal conductivity data of high accuracy cover the much more restricted temperature range from 100 to 400 K and the correlation of this property is limited to that range. Above room temperature, the uncertainty in the correlated values is no more than ±0.5%, but below room temperature it rises to one of ±1.5%. An attempt has also been made to represent the viscosity data by means of a correlation universal among several other polyatomic gases but it has proven unsatisfactory. An extension of the temperature range of the thermal conductivity correlation based upon the Wang Chang and Uhlenbeck kinetic theory also fails to produce acceptable results.

Thermodynamic Properties of Ethylene from the Freezing Line to 450 K at Pressures to 260 MPa

Abstract: A new fundamental equation explicit in Helmholtz energy for thermodynamic properties of ethylene from the freezing line to 450 K at pressures to 260 MPa is presented. Independent equations for the vapor pressure for the saturated liquid and vapor densities as functions of temperature, and for the ideal gas heat capacity are also included. The fundamental equation was selected from a comprehensive function of 100 terms on the basis of a statistical analysis of the quality of the fit. The coefficients of the fundamental equation were determined by a weighted least‐squares fit to selected P‐ρ‐T data, saturated liquid, and saturated vapor density data to define the phase equilibrium criteria for coexistence, Cv data, velocity of sound data, and second virial coefficient data. The fundamental equation and the derivative functions for calculating internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp), and velocity of sound are included. Tables of thermodynamic properties o...

Thermodynamic properties of twenty-one monocyclic hydrocarbons

Abstract: The available structural parameters, fundamental frequencies, and relative energies of different stable conformers, if any, for cyclopropane, cyclopropene, cyclobutane, cyclobutene, 1,3‐cyclobutadiene, cyclopentane, cyclopentene, 1,3‐cyclopentadiene, cyclohexane, cyclohexene, 1,3‐cyclohexadiene, 1,4‐cyclohexadiene, cycloheptane, cycloheptene, 1,3‐cycloheptadiene, 1,3,5‐cycloheptatriene, cyclooctane, cyclooctene, 1,3‐cyclooctadiene, 1,5‐cyclooctadiene, and 1,3,5,7‐cyclooctatetraene were critically evaluated and the recommended values selected. Molecular constants for some molecules were estimated as the experimental values for these compounds are not available. This information was utilized to calculate the ideal gas thermodynamic properties C○p, S○, −(G○−H○0)/T, H○−H○0, and log Kf from 100 to 1500 K. The thermal functions were obtained using the rigid‐rotor harmonic‐oscillator approximation. The contributions derived for the inversion motion of cyclobutane and cyclopentene were obtained from energy levels...

New International Formulations for the Thermodynamic Properties of Light and Heavy Water

Abstract: The General Assembly of the International Association for the Properties of Steam (IAPS), meeting at the 10th International Conference on the Properties of Steam in Moscow in September 1984, adopted new formulations for the thermodynamic properties of fluid H2O and D2O The new formulations have been designated as the IAPS Formulation 1984 for the Thermodynamic Properties of Ordinary Water Substance for Scientific and General Use and the IAPS Formulation 1984 for the Thermodynamic Properties of Heavy Water Substance In this paper we present and discuss these new formulations

Evaluated Kinetic Data for High‐Temperature Reactions. Volume 5. Part 1. Homogeneous Gas Phase Reactions of the Hydroxyl Radical with Alkanes

Abstract: The available kinetic data for the homogeneous gas phase reactions of the hydroxyl radical with alkanes have been compiled and critically evaluated. For each reaction, relevant thermodynamic data, a table of measured rate constants, a discussion of the data, and a comprehensive bibliography are presented. Wherever possible the preferred rate parameters are given with their associated error limits and temperature ranges.

Rate Constants for Reactions of Radiation‐Produced Transients in Aqueous Solutions of Actinides

Abstract: Rate constants have been critically compiled for reactions of ions of the actinides Am, Cf, Cm, Np, Pu, Th, and U, as well as the element Tc, in different oxidation states with various chemical species in aqueous solution. The reactants include products of the radiolysis of water (hydrated electrons, hydrogen atoms, hydroxyl radicals, hydrogen peroxide) and transient species derived from other solutes (e.g., carbonate radical). The data are useful in the estimation of migration properties of actinides, which are relevant to waste management studies.

Computer Methods Applied to the Assessment of Thermochemical Data. Part 1. The Establishment of a Computerized Thermochemical Data Base Illustrated by Data for TiCl4(g), TiCl4(l), TiCl3(cr), and TiCl2(cr)

Abstract: Computer methods are described for the storage, retrieval, and processing of large amounts of thermochemical data and related textual material. The procedures are illustrated by a critical evaluation of data for TiCl4(g), TiCl4(l), TiCl3(cr), and TiCl2(cr); values for standard enthalpies of formation and entropies at 298.15 K are selected for these species.

Recent Progress in Deuterium Triple-Point Measurements

Abstract: The triple point of deuterium is a proposed reference for defining the temperature scale between 13.81 and 24.562 K. We review recent measurements of this fixed point; our discussion concentrates on experiments with samples confined in transportable sealed cells. We also present theoretical estimates of the dependence of the triple‐point temperature on the spin composition of the sample. Satisfactory agreement is obtained with experimental data on deuterium at low concentrations of the para (J=1) species. Present results support the adoption of the triple point of e‐D2 as a standard temperature reference.