Datasets in digital electronic formats are provided for data contained in the publication "Recommended Values for the Gas Phase Enthalpies of Formation of Hydrogen-Oxygen Species;" J. Res. Natl. Inst. Stand. Technol. 121, 108-138 (2016); DOI: 10.6028/jres.121.005.
In this work, we have compiled gas phase enthalpies of formation for nine hydrogen-oxygen species (HxOy) and selected values for use. The compilation consists of values derived from experimental measurements, quantum chemical calculations, and evaluations. This work updates the recommended values in the NIST-JANAF (1985) and Gurvich et al (1989) thermochemical tables for seven species. For two species, HO3 and H2O3 (important in atmospheric chemistry) and not found in prior thermochemical evaluations, we also provide tables of thermochemical functions (Cp, S°, H°, and ΔfH°) as a function of temperature. In this work, we also provide supplementary data for the species consisting of zero point energies, vibrational frequencies, and ion reaction energetics.
In this work, we have compiled gas phase enthalpies of formation for nine hydrogen-oxygen species (HxOy) and selected values for use. Compared to uncertainties for the recommended values in the NIST-JANAF tables (1998) and the thermochemical tables of Gurvich et al (1989), the updated values are (50 to 100) times more precise for H atom, O atom, and O3, (5 to 10) times more precise for OH and HO2, and (25 to 35)% more precise for H2O and H2O2. Enthalpies of formation for the species HO3 and H2O3, which are important in atmospheric chemistry, are not found in prior thermochemical evaluations. For these species, we also provide tables of thermochemical functions (Cp, S°, H°, and ΔH°) as a function of temperature (along with recommended molecular geometries and vibrational frequencies).
This compilation of gas phase enthalpies of formation consists of values derived from experimental measurements, quantum chemical calculations, and evaluations. We list not only recent, more precise values, but older values for archival purposes. Uncertainties (where available) are given along with the enthalpies of formation. The uncertainties listed are in general 2σ (a coverage factor of 2 having a level of confidence of approximately 95%). Some workers did not explicitly state whether the uncertainties are 1σ (standard uncertainty) or 2σ – in these cases, we provide the uncertainties as reported.
In the tables of enthalpies of formation for each species, we also identify the (experimental or computational) method used to derive the enthalpies of formation. A glossary for the notations used in the methods is provided. In the tables comments, we provide the reported values for dissociation energies, heats of reaction, appearance energies, or other quantities used to derive the enthalpy of formation. We provide these values in the original reported units. We utilized the following conversion factors: 1 kJ mol-1 ≡ 83.593472(4) cm-1, 1 eV ≡ 96.4853365(21) kJ mol-1, 1 eV ≡ 8065.544005(50) cm-1, 1 hartree ≡ 2625.49962(13) kJ mol-1, and Rydberg Constant (R8) ≡ 109737.31568539(55) cm-1 taken from the CODATA values for the fundamental constants by Mohr et al and 1 kcal mol-1 ≡ 4.184 kJ mol-1 from the NIST-JANAF tables.
Many of the values selected for the HxOy species are based on the ATcT (Active Thermochemical Tables) thermochemical network approach of Ruscic and coworkers. We only include those ATcT values from published work and not those available only online (which have no documentation nor references).
For each of the species, we provide a table of gas phase enthalpies of formation along with a short discussion. This is followed by a summary table of the selected values of the enthalpies of formation.
In addition to the compilation of gas phase enthalpies of formation for these hydrogen-oxygen species, we provide supplementary data consisting of zero point energies, vibrational frequencies, and ion reaction energetics. Zero point energies (ZPEs) are necessary when deriving ground state total atomization energies (ΣD0) used to compute enthalpies of formation ΔfH°(0 K) from electronic total atomization energies (ΣDe) obtained from quantum chemical calculations. We also provide a table with vibrational frequencies, both experimental fundamental (anharmonic) frequencies and calculated (or derived) harmonic frequencies. In addition, we provide ion reaction energetics, such as ionization energies, electron affinities, and appearance energies. These quantities are utilized to compute enthalpies of formation using thermochemical cycles involving ion processes.
RECORD | |
Creator: | Donald R. Burgess, Jr. |
Publisher: | National Institute of Standards and Technology |
Date: | April 4, 2016 (created); April 8, 2016 (modified) |
Version: | 1.1 |
ResourceType: | dataset |
ContentTypes: | table; (open-standard data-interchange) |
Formats: | xls; (json) |
Size: | 150KB |
DOI: | 10.6028/something (link) |
Citation: | Donald R. Burgess, Jr.; "An Evaluation of Gas Phase Enthalpies of Formation for Hydrogen-Oxygen (HxOy) Species"; J. Res. Natl. Inst. Stand. Technol. 121, 108-138 (2016). |
CitationDOI: | 10.6028/jres.121.005 (link) |
SUBJECTS | |
Objective: | Recommended values for the enthalpy of formation of hydrogen-oxygen species |
Topics: | Standard reference data; Critical evaluation; Data compiliation; Thermochemical database |
Keywords: | ab initio thermochemistry; atomization energies; bond dissociation energies; enthalpy of formation; hydrogen-oxygen species; thermochemical network; thermodynamic properties |
COMPONENTS | |
Compound Class: | Hydrogen-Oxygen Species |
Compounds: | H Atom; O Atom, OH, H2O, HO2, H2O2, O3, HO3, H2O3 |
DATATYPES | |
Datatype: | Thermochemical Data |
Analysis: | Critical Evaluation |
Quantities: | Enthalpy of formation; Ionization energy; Electron affinity; Appearance energy; Ion pair formation energy; Zero point energy |
Datasets: | (1) Enthalpy of Formation; (2) Recommended Enthalpy of Formation; (3) Zero Point Energy; (4) Vibrational Frequency; (5) Ion Thermochemical Energy |
FILES:
FORMAT | SIZE | FILE | DESCRIPTION |
xls | 150KB | Enthalpies-HydrogenOxygen-BurgessD.xlsx | Contains 5 datasets, metadata, dictionary, and references. |