The NIST Chemistry WebBook provides users with easy access to chemical and physical property data for chemical species through the internet. The data provided in the site are from collections maintained by the NIST Standard Reference Data Program and outside contributors. Data in the WebBook system are organized by chemical species. The WebBook system allows users to search for chemical species by various means. Once the desired species has been identified, the system will display data for the species. Data include thermochemical properties of species and reactions, thermophysical properties of species, and optical, electronic and mass spectra.

The NIST Computational Chemistry Comparison and Benchmark Database is a collection of experimental and ab initio thermochemical properties for a selected set of gas-phase molecules. The goals are to provide a benchmark set of experimental data for the evaluation of ab initio computational methods and allow the comparison between different ab initio computational methods for the prediction of gas-phase thermochemical properties. The data files linked to this record are a subset of the experimental data present in the CCCBDB.

The NIST Computational Chemistry Comparison and Benchmark Database is a collection of experimental and ab initio thermochemical properties for a selected set of gas-phase molecules. The goals are to provide a benchmark set of experimental data for the evaluation of ab initio computational methods and allow the comparison between different ab initio computational methods for the prediction of gas-phase thermochemical properties. The data files linked to this record are a subset of the experimental data present in the CCCBDB.

Recommended values are provided for chemical thermodynamic properties of inorganic substances and for organic substances usually containing only one or two carbon atoms. Where available, values are given for the enthalpy of formation, Gibbs energy of formation, entropy, and heat capacity at 298.15 K (25 degrees C), the enthalpy difference between 298.15 and 0 K and the enthalpy of formation at 0 K. All values are given in SI units and are for a standard state pressure of 100 000 pascal. This volume is a new collective edition of "Selected Values of Chemical Thermodynamic Properties," which was issued serially as National Bureau of Standards Technical Notes 270-1 (1965) to 270-8 (1981). Values are given for properties of gaseous, liquid and crystalline substances, for solutions in water, and for mixed aqueous and organic solutions. Values are not given for alloys or other solid solutions, fused salts or for substances of undefined composition. Compounds of the transuranium elements are not included.

Recommended values are provided for chemical thermodynamic properties of inorganic substances and for organic substances usually containing only one or two carbon atoms. Where available, values are given for the enthalpy of formation, Gibbs energy of formation, entropy, and heat capacity at 298.15 K (25 degrees C), the enthalpy difference between 298.15 and 0 K and the enthalpy of formation at 0 K. All values are given in SI units and are for a standard state pressure of 100 000 pascal. This volume is a new collective edition of "Selected Values of Chemical Thermodynamic Properties," which was issued serially as National Bureau of Standards Technical Notes 270-1 (1965) to 270-8 (1981). Values are given for properties of gaseous, liquid and crystalline substances, for solutions in water, and for mixed aqueous and organic solutions. Values are not given for alloys or other solid solutions, fused salts or for substances of undefined composition. Compounds of the transuranium elements are not included.

This document is part of a series of reports describing experimental property measurements completed at the National Institute for Petroleum and Energy Research (NIPER) in Bartlesville, Oklahoma, in the 1980s and 1990s. Members of the Bartlesville Thermodynamics Group included William D. "Bill" Good, William V. "Bill" Steele, Bruce E. Gammon, Norris K. Smith, Stephen E. Knipmeyer, An "Andy" Nguyen, Timothy D. Klots, I. A. "Alex" Hossenlopp, Aaron P. Rau, William B. Collier, John F. Messerly, Ann G. Osborn, Susan Lee-Bechtold, Donald G. Archer, Ian R. Tasker, Allan B. Cowell, Michael M. Strube, and the author of this report.

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 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 ?fH°) 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.

This document is part of a series of reports describing experimental property measurements completed at the National Institute for Petroleum and Energy Research (NIPER) in Bartlesville, Oklahoma, in the 1980s and 1990s. Members of the Bartlesville Thermodynamics Group included William D. "Bill" Good, William V. "Bill" Steele, Bruce E. Gammon, Norris K. Smith, Stephen E. Knipmeyer, An "Andy" Nguyen, Timothy D. Klots, I. A. "Alex" Hossenlopp, Aaron P. Rau, William B. Collier, John F. Messerly, Ann G. Osborn, Susan Lee-Bechtold, Donald G. Archer, Ian R. Tasker, Allan B. Cowell, Michael M. Strube, and the author of this report.

This data deposit contains JSON files of phase-shift data and related quantities for pair interactions using state-of-the-art pair potentials for helium (isotopes of mass 3 and 4 and their cross interaction), neon (all six interactions among isotopes with masses 20, 21, and 22), and argon (the dominant isotope of mass 40). A Python program is supplied to compute the second virial coefficient B(T), its first two temperature derivatives, and the second acoustic virial coefficient for any of these pair interactions at temperatures up to 1500 K. The lower temperature limit is 0.01 K for helium, 1 K for neon, and 10 K for argon. Another program is supplied to calculate these quantities for neon of natural isotopic composition.This work is described in a paper: G. Garberoglio and A.H. Harvey, "Avoiding Interpolation Errors for Computed Second Virial Coefficients of Noble Gases", Metrologia, in preparation (2025).The code and data files are also maintained at this Github site:https://github.com/gioGarbe/TAPPS

This data deposit contains JSON files of phase-shift data and related quantities for pair interactions using state-of-the-art pair potentials for helium (isotopes of mass 3 and 4 and their cross interaction), neon (all six interactions among isotopes with masses 20, 21, and 22), and argon (the dominant isotope of mass 40). A Python program is supplied to compute the second virial coefficient B(T), its first two temperature derivatives, and the second acoustic virial coefficient for any of these pair interactions at temperatures up to 1500 K. The lower temperature limit is 0.01 K for helium, 1 K for neon, and 10 K for argon. Another program is supplied to calculate these quantities for neon of natural isotopic composition.This work is described in a paper: G. Garberoglio and A.H. Harvey, "Avoiding Interpolation Errors for Computed Second Virial Coefficients of Noble Gases", Metrologia, in preparation (2025).The code and data files are also maintained at this Github site:https://github.com/gioGarbe/TAPPS