Showing papers in "Journal of Physical and Chemical Reference Data in 1989"

Reduction Potentials of One-Electron Couples Involving Free Radicals in Aqueous Solution

Abstract: Reduction of an electron acceptor (oxidant), A, or oxidation of an electron donor (reductant), A2 −, is often achieved stepwise v i a one‐electron processes involving the couples A/A⋅− or A⋅−/A2 − (or corresponding prototropic conjugates such as A/AH⋅ or AH⋅/AH2). The intermediate A⋅−(AH⋅) is a free radical. The reduction potentials of such one‐electron couples are of value in predicting the direction or feasibility, and in some instances the rate constants, of many free‐radical reactions.Electrochemical methods have limited applicability in measuring these properties of frequently unstable species, but fast, kinetic spectrophotometry (especially pulse radiolysis) has widespread application in this area. Tables of c a. 1200 values of reduction potentials of c a. 700 one‐electron couples in aqueous solution are presented. The majority of organic oxidants listed are quinones, nitroaryl and bipyridinium compounds. Reductants include phenols, aromatic amines, indoles and pyrimidines, thiols and phenothiazines. Inorganic couples largely involve compounds of oxygen, sulfur, nitrogen and the halogens. Proteins, enzymes and metals and their complexes are excluded.

Evaluated Kinetic and Photochemical Data for Atmospheric Chemistry: Supplement VI. IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry

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)]. The present evaluation is limited to the following families of atmospherically important reactions: Ox, HOx, NOx, and SOx. 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 151 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...

Standard Electrode Potentials and Temperature Coefficients in Water at 298.15 K

Abstract: A great deal of solution chemistry can be summarized in a table of standard electrode potentials of the elements in the solvent of interest. In this work, standard electrode potentials and temperature coefficients in water at 298.15 K, based primarily on the ‘‘NBS Tables of Chemical Thermodynamic Properties,’’ are given for nearly 1700 half‐reactions at pH=0.000 and pH=13.996. The data allow the calculation of the thermodynamic changes and equilibrium constants associated with ∼1.4 million complete cell reactions over the normal temperature range of liquid water. Estimated values are clearly distinguished from experimental values, and half‐reactions involving doubtful chemical species are duly noted. General and specific methods of estimation of thermodynamic quantities are summarized.

Octanol‐Water Partition Coefficients of Simple Organic Compounds

Abstract: Octanol‐water partition coefficients (log P) for 611 simple organic compounds representing all principal classes have been retrieved from the literature. Available experimental details of measurement are documented from original articles. Pertinent thermodynamic relations are presented, with a discussion of direct and indirect methods of measurement. Reported log P data for each compound have been evaluated according to stated criteria, and recommended values (with uncertainty) are given.

Evaluated kinetic and photochemical data for atmospheric chemistry: supplement III

Abstract: Here we present the summary Table of reactions containing the recommended rate coefficients along with the assigned error limits. The reader is referred to the full article to obtain the data sheets for each reaction which contain the available experimental data upon which the recommendations are based

A Fundamental Equation for Water Covering the Range from the Melting Line to 1273 K at Pressures up to 25 000 MPa

Abstract: In order to represent the thermodynamic properties of water (H2O) over an extremely large range of temperature and pressure that is not covered by existing equations of state, a new fundamental equation has been developed. The Helmholtz function was fitted to the following kinds of experimental data: (a) pρT data, (b) thermal properties of the saturation curve (ps,ρ’,ρ‘), (c) speed of sound w, (d) isobaric heat capacity cp, (e) isochoric heat capacity cv, (f) differences of the internal energy u, (g) differences of the enthalpy h, (h) Joule–Thomson coefficient μ, and (i) the isothermal throttling coefficient δT. A new statistical selection method was used to determine the final form of the equation from a ‘‘bank’’ of 630 terms which also contained functional forms that have not been previously used. This 58‐coefficient equation covers the entire fluid region from the melting line to 1273 K at pressures up to 25 000 MPa, and represents the data within their experimental accuracy also in the ‘‘difficult’’ r...

Thermodynamic Properties of Argon from the Triple Point to 1200 K with Pressures to 1000 MPa

Abstract: A new thermodynamic property formulation for argon is presented. The formulation includes a fundamental equation explicit in Helmholtz energy, a vapor pressureequation, and estimating functions for the densities of saturated liquid and vapor states. The coefficients of the fundamental equation and ancillary functions were determined by a weighted least‐squares fit of selected experimental data using a statistical procedure to select the terms for the equation most appropriate for the representation of the data. In determining the coefficients of the fundamental equation, multi‐property fitting methods were used to represent pressure‐density‐temperature data, saturated liquid and saturated vapor densities, and velocity of sound measurements. The fundamental equation is valid for liquid and vapor phases except near the critical point. The equation has been developed to conform to the Maxwell criterion for two‐phase liquid–vapor equilibrium states. Comparisons between the data used to determine the fundamental equation and values calculated from the formulation are given to verify the accuracy of the fundamental equation. The formulation given here may be used to calculate pressures and densities generally with an accuracy of ±0.1%, heat capacities within ±3%, and velocity of sound within ±2% except near the critical point. Tables of thermodynamic properties of argon calculated with the formulation presented here are given for fluid states within the range of validity of the correlation.

Thermophysical Properties of Methane

Abstract: New correlations for the thermophysical properties of fluid methane are presented. The correlations are based on a critical evaluation of the available experimental data and have been developed to represent these data over a broad range of the state variables. Estimates for the accuracy of the equations and comparisons with measured properties are given. The reasons for this new study of methane include significant new and more accurate data, and improvements in the correlation functions which allow increased accuracy of the correlations especially in the extended critical region. For the thermodynamic properties, a classical equation for the molar Helmholtz energy, which contains terms multiplied by the exponential of the quadratic and quartic powers of the system density, is used. The resulting equation of state is accurate from about 91 to 600 K for pressures <100 MPa and was developed by considering PVT, second virial coefficient, heat capacity, and sound speed data. Tables of coefficients and equatio...

Thermodynamic and Transport Properties of Carbohydrates and their Monophosphates: The Pentoses and Hexoses

Abstract: This review contains recommended values of the thermodynamic and transport properties of the five and six membered ring carbohydrates and their phosphates in both the condensed and aqueous phases. Equilibrium data, enthalpies,heat capacities, and entropies have been collected from the literature. The accuracy of these data have been assessed, adjusted to 298.15 K and to a common standard state, and entered into a catalog of thermochemical reactions. The solution of this reaction catalog yields a set of recommended values for the formation properties of these substances. The volumetric data have also been critically evaluated. Recommended values are presented for standard state molar volumes and the temperature and pressure derivatives of the molar volume, i. e., the expansivity and the compressibility. The excess property data of aqueous solutions of these substances have been correlated to yield recommended values of the parameters of the virial expansion model used to represent the data. The transport data considered here includes both viscosity and diffusion data of aqueous solutions of the carbohydrates. The available phase diagram data and transition temperatures are summarized.

Rate Constants for the Quenching of Excited States of Metal Complexes in Fluid Solution

Abstract: The rate constants for the quenching of the excited states of metal ions and complexes in homogeneous fluid solution are reported in this compilation. Values of kq for dynamic, collisional processes between excited species and quenchers have been critically evaluated, and are presented with the following information, among others, from the original publications, when available: description of the solution medium, temperature at which kq was determined, experimental method, range of quencher concentration used, lifetime of the excited state in the absence of quencher, activation parameters, quenching mechanism. Data collection is complete through the end of 1986, and covers the coordination compounds of 26 metals, including the ions and complexes of the inner‐ and outer‐transition metals, and porphyrin complexes of nontransition metals. Data for 261 excited states quenched by more than 400 inorganic quenchers and 600 organic quenchers have been extracted from almost 500 publications. The introduction to th...

Evaluation of Data on Solubility of Simple Apolar Gases in Light and Heavy Water at High Temperature

Abstract: The solubility data of apolar gases in light and heavy water over the temperature range covered experimentally have been evaluated, laying particular emphasis to the region above the normal boiling points of the solvents. The systems that have been included in this work are the inert gases and CH4 in light water and heavy water, H2, O2, N2, and C2H6 in light water and D2 in heavy water. Data in the original sources have been brought to the same footing by calculating from the raw experimental data P, T, and x when they were not reported by the author. This step is considered necessary to assess critically the available sets of data. The temperature dependence of Henry’s constants for all the binary systems have been expressed in terms of two different polynomial equations. The formulations presented are discussed and the limits of application given.

Cross Sections for K-shell X-ray Production by Hydrogen and Helium Ions in Elements from Beryllium to Uranium

Abstract: Experimental cross sections for K‐shell x‐ray production by hydrogen and helium ions (Z1=1,2) in target atoms from beryllium to uranium (Z2=4–92 ) are tabulated as compiled (7418 cross sections) from the literature (161 references were found) with the search for the data terminated in January 1988. These cross sections are compared with predictions of the first Born approximation and ECPSSR theory for inner‐shell ionization. The ECPSSR accounts for the energy loss (E) and Coulomb deflection (C) of the projectile ion as well as for the perturbed stationary state (PSS) and relativistic (R) nature of the target’s inner‐shell electron. While the first Born approximation generally overestimates the data by orders of magnitude, the ECPSSR theory is confirmed to be, on the average, in agreement with the experiment to within 10%–20%. For light and heavy target atoms, however, systematic and opposite deviations are found in the low projectile‐velocity regime. These deviations are associated with the influence of m...

The Thermal Conductivity of Nitrogen and Carbon Monoxide in the Limit of Zero Density

Abstract: The paper presents accurate representations for the thermal conductivity of the diatomic gases nitrogen and carbon monoxide in the limit of zero density. These gases were studied because they have nearly the same molecular mass and viscosities. In contrast, the new analysis confirms that the thermal conductivities of the two gases differ remarkably, especially at low temperatures. The theoretically‐based correlations provided are valid for the temperature range 220–2100 K and have associated uncertainties of ±1% between 300 and about 500 K, rising to ±2.5% at the low‐ and high‐temperature extremes. A comparison with some empirical and semiempirical correlations is given.

Photoemission Cross Sections for Atomic Transitions in the Extreme Ultraviolet due to Electron Collisions with Atoms and Molecules

Abstract: This article reviews experimental photoemission cross sections in the extreme ultraviolet, for transitions in excited atoms and atomic ions formed in electron collisions with atoms and molecules A survey of the available experimental data for each investigated target gas reveals severe inconsistencies between cross sections reported by different laboratories As almost all reported cross sections are based on relative measurements, a detailed discussion is given of the methods used for normalization of the cross sections

Microwave Spectral Tables. III. Hydrocarbons, CH to C10H10

Abstract: All of the rotational spectral lines observed and reported in the open literature for 91 hydrocarbon molecules have been tabulated. This isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported. In addition to correcting a number of misprints and errors in the literature cited, the spectral lines for many normal isotopic species have been refit to produce a comprehensive and consistent analysis of all the data extracted from various literature sources. The derived molecular properties, such as rotational and centrifugal distortion constants, hyperfine structure constants, electric dipole moments, and rotational g‐factors are listed.

Standard Chemical Thermodynamic Properties of Polycyclic Aromatic Hydrocarbons and Their Isomer Groups. II. Pyrene Series, Naphthopyrene Series, and Coronene Series

Abstract: The tables in our first paper on polycyclic aromatic hydrocarbons [J. Phys. Chem. Ref. Data 17, 241 (1988)] have been extended by calculating thermodynamic properties for the first four isomer groups in the pyrene series, the first three isomer groups in the naphthopyrene series, and the first three isomer groups in the coronene series. Successive isomer groups in each series differ by C4H2. Since chemical thermodynamic properties are known for only a limited number of polycyclic aromatic hydrocarbons, the properties of individual species have been estimated using Benson group values of Stein and Fahr for temperatures from 298.15 to 3000 K. Values of C○P , S°, Δf H°, and Δf G° have been calculated in joules for a standard state pressure of 1 bar. The chemical thermodynamic properties of the individual species have also been calculated. The isomer group values provide a basis for extrapolating to higher carbon numbers where it is not feasible to consider individual molecular species.

Thermodynamic Properties of Dioxygen Difluoride (O2F2) and Dioxygen Fluoride (O2F)

Abstract: Recent spectroscopic and chemical kinetic studies have provided sufficient data for construction of reliable thermodynamic tables for both dioxygen difluoride (O2F2; Chemical Abstracts Registry Number, 7783‐44‐0) and dioxygen fluoride (O2F; Chemical Abstracts Registry Number, 15499‐23‐7). This paper contains those tables for these species in both SI units (0.1 MPa standard state) and cal K mol units (1.0 atm standard state). The experimental basis includes three recent assignments of the fundamental vibrational frequencies for O2F2, a new set of rotational constants for O2F, an enthalpy change for dissociation of O2F, and an updated standard enthalpy of formation for O2F2.

Thermal Conductivity of Refrigerants in a Wide Range of Temperature and Pressure

Abstract: Thermal conductivities of refrigerant 12 (dichlorodifluoromethane), refrigerant 113 (1,1,2‐trichloro‐1,2,2‐trifluoroethane), refrigerant 114 (1,2‐dichloro‐1,1,2,2‐tetrafluoroethane), and refrigerant C318 (perfluorocyclobutane) were critically evaluated and correlated on the basis of a comprehensive literature survey. Recommended values were established for a wide range of temperatures and pressures, extending up to three times the critical density and excluding the critical region. Using the residual concept, a dilute‐gas function and an excess function of simple form were developed for each refrigerant. The average accuracy obtained is ∼6%.