Showing papers in "Journal of Physical and Chemical Reference Data in 1999"

A New Equation of State for Argon Covering the Fluid Region for Temperatures From the Melting Line to 700 K at Pressures up to 1000 MPa

Abstract: This work reviews the available data on thermodynamic properties of argon and presents a new equation of state in the form of a fundamental equation explicit in the Helmholtz energy. The functional form of the residual part of the Helmholtz energy was developed by using state-of-the-art linear optimization strategies and a new nonlinear regression analysis. The new equation of state contains 41 coefficients, which were fitted to selected data of the following properties: (a) thermal properties of the single phase (pρT) and (b) of the liquid–vapor saturation curve (ps, ρ′, ρ″) including the Maxwell criterion, (c) speed of sound w, isochoric heat capacity cv, second and third thermal virial coefficients B and C and second acoustic virial coefficient βa. For the density, the estimated uncertainty of the new equation of state is less than ±0.02% for pressures up to 12 MPa and temperatures up to 340 K with the exception of the critical region and less than ±0.03% for pressures up to 30 MPa and temperatures bet...

Evaluated Chemical Kinetics Data for Reactions of N(2D), N(2P), and N2(A 3Σu+) in the Gas Phase

Abstract: Chemical kinetics data for the gas phase reactions of the first two electronically excited states of atomic nitrogen: N(2D) and N(2P), and of the first excited state of molecular nitrogen N2(A 3Σu+) are compiled and evaluated The experimental data for 127 reactions are summarized, the experimental method and year of publication given, a recommended value given for the rate constant for each reaction at 298 K, and where possible, its temperature dependence The reaction mechanisms are discussed within the limits of the available quantitative product yield data The literature has been covered through early 1999 There are 94 references

Evaluation of Calculated and Measured Electron Inelastic Mean Free Paths Near Solid Surfaces

Abstract: An analysis is given of the consistency of calculated and measured electron inelastic mean free paths (IMFPs) near solid surfaces for electron energies between 50 and 104 eV, the energy range of relevance for surface analysis by Auger electron spectroscopy and x-ray photoelectron spectroscopy. This evaluation is based on IMFPs calculated from experimental optical data and on IMFPs measured by elastic-peak electron spectroscopy (EPES). We describe the methods used for the calculations and measurements, and we identify the various sources of uncertainty. Most of our evaluation is based on IMFPs for seven elemental solids (Al, Si, Ni, Cu, Ge, Ag, and Au) for which there were at least two sources of IMFP calculations and at least two sources of IMFP measurements for each solid. Our comparison of the calculated IMFPs showed a high degree of consistency for Al, Ni, Cu, Ag, and Au. The comparison of measured IMFPs showed greater scatter than for the calculated IMFPs, but reasonable consistency was found for the ...

CODATA Recommended Values of the Fundamental Physical Constants 1998*$\dagger$

Abstract: This paper gives the 1998 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology ~CODATA! for international use. Further, it describes in detail the adjustment of the values of the subset of constants on which the complete 1998 set of recommended values is based. The 1998 set replaces its immediate predecessor recommended by CODATA in 1986. The new adjustment, which takes into account all of the data available through 31 December 1998, is a significant advance over its 1986 counterpart. The standard uncertainties ~i.e., estimated standard deviations ! of the new recommended values are in most cases about 1/5 to 1/12 and in some cases 1/160 times the standard uncertainties of the corresponding 1986 values. Moreover, in almost all cases the absolute values of the differences between the 1998 values and the corresponding 1986 values are less than twice the standard uncertainties of the 1986 values. The new set of recommended values is available on the World Wide Web at physics.nist.gov/ constants. ©1999 American Institute of Physics and American Chemical Society. @S0047-2689 ~00!00301-9#

Evaluated Kinetic and Photochemical Data for Atmospheric Chemistry, Organic Species: Supplement VII

Abstract: This paper updates and extends part of the previous data base of critical evaluations of the kinetics and photochemistry of gas-phase chemical reactions of neutral species involved in atmospheric chemistry [J. Phys. Chem. Ref. Data 9, 295 (1980); 11, 327 (1982); 13, 1259 (1984); 18, 881 (1989); 21, 1125 (1992); 26, 521 (1997); 26, 1329 (1997)]. The present evaluation is limited to the organic family of atmospherically important reactions. The work has been carried out by the authors under the auspices of the IUPAC Subcommittee on Gas Phase Kinetic Data Evaluation for Atmospheric Chemistry. Data sheets have been prepared for 171 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each thermal reaction, a preferred value of the rate coefficient at 298 K is given together with a temperature dependence where possible. The selection of the preferred value is discussed and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. For each photochemical reaction the data sheets list the preferred values of the photoabsorption cross sections and the quantum yields of the photochemical reactions together with comments on how they were selected. The data sheets are intended to provide the basic physical chemical data needed as input for calculations which model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an Appendix listing the available values of enthalpies of formation of the reactant and product species.

Thermodynamic Properties of the KCl+H2O System

Abstract: The thermodynamic properties of the KCl+H2O system were examined in order to provide: (1) an improved equation for the osmotic coefficient as a function of molality and temperature for purposes of isopiestic measurements, (2) a determination of the thermodynamic properties of the standard-state solution process, and (3) a test of the accuracy of the enthalpy of solution values for KCl(cr), a calorimetric standard. New equations that describe the thermodynamic properties of the KCl+H2O system were obtained from previously published measurements for this system. The measured values included in the fitted equations spanned the range of temperature from approximately 260 to 420 K for KCl(aq) and 1.5 K to 1033.7 K for KCl(cr). New equations and/or values for the following properties are given in the present work: (1) thermal properties of KCl(cr) from 0 K to the melting point, 1045 K, (2) the change in chemical potential for both KCl and H2O in KCl(aq) as a function of temperature, and molality, valid from 260...

Electron Interactions With Plasma Processing Gases: An Update for CF4, CHF3, C2F6, and C3F8

Abstract: An update of electron–collision cross sections and electron transport parameters is presented for CF4, CHF3, C2F6, and C3F8.

Estimating Solid-Liquid Phase Change Enthalpies and Entropies

Abstract: A group additivity method based on molecular structure is described that can be used to estimate solid–liquid total phase change entropy (Δ0TfusStpce) and enthalpy (Δ0TfusHtpce) of organic molecules. The estimation of these phase changes is described and numerous examples are provided to guide the user in evaluating these properties for a broad range of organic structures. A total of 1858 compounds were used in deriving the group values and these values are tested on a database of 260 additional compounds. The absolute average and relative errors between experimental and calculated values for these 1858 compounds are 9.9 J⋅mol−1⋅K−1 and 3.52 kJ⋅mol−1, and 0.154 and 0.17 for Δ0TfusStpce and Δ0TfusHtpce, respectively. For the 260 test compounds, standard deviations of ±13.0 J⋅mol−1⋅K−1(Δ0TfusStpce) and ±4.88 kJ mol−1(Δ0TfusHtpce) between experimental and calculated values were obtained. Estimations are provided for both databases. Fusion enthalpies for some additional compounds not included in the statistic...

Electron Interactions With Cl2

Abstract: Low-energy electron interactions with the Cl2 molecule are reviewed Information is synthesized and assessed on the cross sections for total electron scattering, total rotational excitation, total elastic electron scattering, momentum transfer, total vibrational excitation, electronic excitation, total dissociation into neutrals, total ionization, total electron attachment, and ion-pair formation Similar data on the density-reduced ionization, density-reduced electron attachment, density-reduced effective ionization, electron transport coefficients, and electron attachment rate constant are also synthesized and critically evaluated Cross sections are suggested for total electron scattering, total elastic electron scattering, total ionization, dissociation into neutrals, electron attachment, and ion-pair formation A cross section is derived for the total vibrational excitation cross section via low-lying negative ion resonances Data are suggested for the coefficients for electron attachment, ionization

IUPAC-NIST Solubility Data Series 70. Solubility of Gases in Glassy Polymers

Abstract: Solubility of gases in polymers is an important property of polymeric materials relevant to many practical applications. Sorption of small molecules in polymers is a fundamental concern in such areas as food packaging, beverage storage, and polymer processing. However, by far the main interest in the solubility of gases in polymers, and especially in glassy polymers, is related to development of novel advanced materials for gas separation membranes. This is because the concentration gradient of a dissolved gas is the driving force of membrane processes. Development of these novel separation methods resulted in a rapid accumulation, in the recent literature, of thermodynamic data related to the solubility of gases in polymers at different temperatures and pressures. Polymers can be regarded as special cases of media intermediate between liquids and solids. As a consequence, modeling of gas sorption in polymers is very difficult and presents a permanent challenge to theoreticians and experimenters. The collection and critical evaluation of solubility data for various gas–polymer systems is relevant to both practical aspects of polymer applications and to fundamental studies of polymer behavior. This volume of the IUPAC-NIST Solubility Data Series summarizes the compilations and critical evaluations of the data on solubility of gases in glassy polymers. It is implied in this edition that “gases” are the components that are either permanent gases (supercitical fluids) or have saturated vapor pressure more than 1 atm at ambient conditions (298 K). The polymeric components of compilations and critical evaluations are primarily high molecular mass, amorphous, linear (noncross-linked) compounds that have the glass transition temperatures above ambient temperature. The data for each gas–polymer system have been evaluated, if the results of at least three independent and reliable studies have been reported. Where the data of sufficient accuracy and reliability are available, values are recommended, and in some cases smoothing equations are given to represent variations of solubility with changes in gas pressure and temperature. Referenced works are presented in the standard IUPAC-NIST Solubility Data Series format. Depending on the gas–polymer system, reported data are given in tabular form or in the form of sorption isotherms. The data included in the volume comprise solubilities of 30 different gases in more than 80 primarily amorphous homo and copolymers. Where available, the compilation or critical evaluation sheets include enthalpies of sorption and parameters for sorption isotherms. Throughout the volume, SI conventions have been employed as the customary units in addition to the units used in original publications.

IUPAC-NIST Solubility Data Series 69. Ternary Alcohol-Hydrocarbon-Water Systems

Abstract: The mutual solubilities of ternary systems containing alcohols, hydrocarbons and water are reviewed. An exhaustive search of the literature was attempted for numerical data on all alcohols and hydrocarbons which are liquid at STP. Data were found for alcohols with up to nine carbon atoms, but mostly with fewer than four carbons. Data for a variety of hydrocarbon structural types were found including alkane, alkene, and arene. A total of 205 original studies treating 116 ternary systems which have been published through 1992 are compiled. For 47 systems sufficient data were available to allow critical evaluation. All solubility data are expressed as mass and mole fractions as well as the originally reported units. Similar reviews of the related binary systems have previously been prepared for the Solubility Data Series.

Phase Diagrams and Thermodynamic Properties of Binary Systems of Drugs

Abstract: The phase diagram data of 60 binary systems of drugs were evaluated with the aid of a computer-coupled phase diagram/thermodynamic analysis. Data for this analysis were obtained by an exhaustive literature search (110 references). Among the results of this analysis are the excess Gibbs energy of liquid and solid solution phases, and the thermodynamic properties of intermediate compounds. For each system a phase diagram was calculated; such calculated diagrams are thermodynamically consistent and are offered as the best constructions which can be deduced from available data.

Thermodynamics of Enzyme-Catalyzed Reactions: Part 6—1999 Update

Abstract: This review serves to update previously published evaluations of equilibrium constants and enthalpy changes for enzyme-catalyzed reactions. For each reaction the following information is given: the reference for the data; the reaction studied; the name of the enzyme used and its Enzyme Commission number; the method of measurement; the conditions of measurement [temperature, pH, ionic strength, and the buffer(s) and cofactor(s) used]; the data and an evaluation of it; and, sometimes, commentary on the data and on any corrections which have been applied to it or any calculations for which the data have been used. The data from 96 references have been examined and evaluated. Chemical Abstract Service registry numbers are given for the substances involved in these various reactions. There is also a cross reference between the substances and the Enzyme Commission numbers of the enzymes used to catalyze the reactions in which the substances participate.

IUPAC-NIST Solubility Data Series 67. Halogenated Ethanes and Ethenes with Water

Abstract: This volume covers the solubilities of halogenated ethanes and ethenes with water, heavy water, seawater, and aqueous electrolyte solutions. All data were critically examined for their reliability and best value estimates were selected on the basis of such evaluations. Referenced works are presented in the standard IUPAC-NIST Solubility Data Series format. Reported and best value data are presented in tabular form and, where justified, data correlation equations and graphical illustrations are provided. Throughout the volume, SI conventions have been employed as the customary units. The importance of these data arises from the fact that halogenated ethanes and ethenes have commercial uses as industrial chemicals, propellants, solvents, and the like. In such applications, often from spillage, leakage, or mishandling, they contact water and are exposed to the atmosphere. The data are essential for concentration estimates for the halogenated ethanes and ethenes in drinking and ground water, foodstuffs, human tissue, marine organisms, and the atmosphere. The halogenated aliphatics are of particular interest to health scientists, engineers, environmentalists, and atmospheric chemists in that they represent a class of chemical materials which has many significant industrial applications. However, at the same time, these substances have been shown, in some cases, to be carcinogenic and also to be especially damaging to the earth’s atmospheric composition through their chemical reactivity which results in atmospheric ozone depletion. The high ozone depletion potentials of this class of chemical substances emphasizes the importance of having available complete, accurate, and reliable data for mutual solubilities with water. The availability of such data is essential for estimates of halogenated hydrocarbon levels in both natural waters and aqueous industrial liquids which result from industrial fabrication, industrial waste removal processes, and the like. The data also provide significant solubility values for studies concerning the health of human and other biological systems.

Revised Thermochemical Properties of Phosphinidene (PH), Phosphine (PH3), Phosphorus Nitride (PN), and Magnesium Phosphate (Mg3P2O8)

Abstract: Revised thermochemical tables for phosphinidene (PH), phosphine (PH3), phosphorus nitride (PN), and magnesium orthophosphate (Mg3P2O8) are computed. These computations were done because the P reference state was not adjusted to the white P reference state and/or because the tables of these compounds are printed erroneously in the 4th edition of the NIST-JANAF Thermochemical Tables.

Thermodynamic Properties of Ideal Gas Nitro and Nitrate Compounds

Abstract: The ideal gas thermodynamic properties of 27 organic nitro and nitrate organic compounds and two of their radicals are presented. Most of these compounds are high explosives (TNT, RDX, HMX, PETN, NPN, and NG), while others serve as propellants or specialty fuels (such as nitromethane). The thermodynamic properties were calculated using fundamental molecular data. The molecular data were gathered from the literature or calculated for this purpose. The enthalpy of formation of gaseous 1-nitropentane was estimated to be −164.431 kJ mol−1 (−39.3±0.5 kcal mol−1); that of 1-nitrohexane to be −185.351 kJ mol−1 (−44.3±0.7 kcal mol−1) for the ideal gas and −241.835 kJ mol−1 (−57.8±0.7 kcal mol−1) for the liquid. All values refer to 298.15 K.

Phase Behavior and Miscibility in Binary Blends Containing Polymers and Copolymers of Styrene, of 2,6-Dimethyl-1,4-Phenylene Oxide, and of Their Derivatives

Abstract: This article presents a comprehensive and systematic survey of miscibility in binary mixtures of polymers and copolymers based on styrene, on 2,6-dimethyl-1,4-phenylene oxide, and on their derivatives. Certain other systems based on methacrylate, acrylonitrile, and maleic anhydride-containing polymers are also included to complete the analysis. Experimental and theoretical studies of miscibility and phase behavior of homopolymer/homopolymer, homopolymer/copolymer, and copolymer/copolymer blends are analyzed. A mean field model is employed to correlate and predict miscibility in new systems. This model is also used to account for the different phenomena governing miscibility/immiscibility behavior, with special reference to the influence of the chemical structure of the polymers. Tables containing experimental data and related details are included for 127 polymer/polymer systems; these tables also contain summaries of the binary phase behavior. Calculated segmental interaction parameters, together with the relevant references and recommended values, are also tabulated.

IUPAC-NIST Solubility Data Series 68. Halogenated Aliphatic Hydrocarbon Compounds C3–C14 With Water

Abstract: This volume covers the solubilities of halogenated aliphatic C3–C14 compounds with water, heavy water, and electrolyte solutions. All data were critically examined for their reliability and best value estimates were selected on the basis of such evaluations. Referenced works are presented in the standard IUPAC-NIST Solubility Data Series format. Reported and best value data are presented in tabular form and, where justified, data correlation equations and graphical illustrations are provided. Throughout the volume, SI conventions have been employed as the customary units. The importance of these data arises from the fact that halogenated aliphatics have considerable commercial uses in a variety of applications such as industrial chemicals, process raw materials, solvents, and the like. In such applications they are often in contact with water and are routinely exposed to the atmosphere. Sometimes such contact and exposure results from spillage, leakage, or mishandling. Reliable data are essential for conc...

Properties of Materials and Systems of Importance to Environmental Fates and Remediation. III. Review of Previous Thermodynamic Property Values for Chromium and Some of its Compounds

Abstract: Twenty-seven (27) crystalline and aqueous chromium species from the NBS Tables of Chemical Thermodynamic Properties were selected based upon their possible importance to environmental fate and remediation processes. Their NBS files were studied to determine the sources of information and the methodology used to determine the NBS selected thermodynamic values. The NBS tables for chromium were compiled in 1966. A literature search was performed to determine the existence of additional data for these species. Documentary data are presented for the thermodynamic properties of these twenty-seven (27) species.