Selected ATcT [1, 2] enthalpy of formation based on version 1.122h of the Thermochemical Network [3] This version of ATcT results was generated from an expansion of version 1.122e [4] to include results centered on the determination of the appearance energy of CH3+ from CH4. [5].
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Species Name |
Formula |
Image |
ΔfH°(0 K) |
ΔfH°(298.15 K) |
Uncertainty |
Units |
Relative Molecular Mass |
ATcT ID |
Methane | CH4 (g) | | -66.557 | -74.526 | ± 0.055 | kJ/mol | 16.04246 ± 0.00085 | 74-82-8*0 |
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Representative Geometry of CH4 (g) |
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spin ON spin OFF |
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Top contributors to the provenance of ΔfH° of CH4 (g)The 20 contributors listed below account only for 81.0% of the provenance of ΔfH° of CH4 (g). A total of 91 contributors would be needed to account for 90% of the provenance.
Please note: The list is limited to 20 most important contributors or, if less, a number sufficient to account for 90% of the provenance. The Reference acts as a further link to the relevant references and notes for the measurement. The Measured Quantity is normaly given in the original units; in cases where we have reinterpreted the original measurement, the listed value may differ from that given by the authors. The quoted uncertainty is the a priori uncertainty used as input when constructing the initial Thermochemical Network, and corresponds either to the value proposed by the original authors or to our estimate; if an additional multiplier is given in parentheses immediately after the prior uncertainty, it corresponds to the factor by which the prior uncertainty needed to be multiplied during the ATcT analysis in order to make that particular measurement consistent with the prevailing knowledge contained in the Thermochemical Network.
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Contribution (%) | TN ID | Reaction | Measured Quantity | Reference | 63.2 | 1888.1 | 2 H2 (g) + C (graphite) → CH4 (g)  | ΔrG°(1165 K) = 37.521 ± 0.068 kJ/mol | Smith 1946, note COf, 3rd Law | 3.7 | 1887.4 | CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)  | ΔrH°(298.15 K) = -890.61 ± 0.21 kJ/mol | Dale 2002 | 2.4 | 1887.6 | CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)  | ΔrH°(298.15 K) = -890.44 ± 0.26 kJ/mol | GOMB Ref Calorimeter, Alexandrov 2002 | 2.3 | 118.2 | 1/2 O2 (g) + H2 (g) → H2O (cr,l)  | ΔrH°(298.15 K) = -285.8261 ± 0.040 kJ/mol | Rossini 1939, Rossini 1931, Rossini 1931b, note H2Oa, Rossini 1930 | 1.3 | 1887.1 | CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)  | ΔrH°(303.15 K) = -889.849 ± 0.350 kJ/mol | Rossini 1931a, Rossini 1931b, Prosen 1945, Rossini 1940, note CH4 | 1.3 | 1887.5 | CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)  | ΔrH°(298.15 K) = -890.43 ± 0.35 kJ/mol | Alexandrov 2002a, Alexandrov 2002 | 0.9 | 1900.13 | CH3 (g) → C (g) + 3 H (g)  | ΔrH°(0 K) = 289.11 ± 0.10 kcal/mol | Feller 2016, note unc2 | 0.8 | 1887.2 | CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)  | ΔrH°(298.15 K) = -890.699 ± 0.430 kJ/mol | Pittam 1972, note CH4a | 0.8 | 1939.1 | CH3 (g) → CH2 (g, triplet) + H (g)  | ΔrH°(0 K) = 109.26 ± 0.08 kcal/mol | Feller 2016, est unc, note unc2 | 0.5 | 1902.4 | CH3 (g) → C (g) + 3 H (g)  | ΔrH°(0 K) = 1209.50 ± 0.56 kJ/mol | Harding 2008 | 0.5 | 1810.2 | CO (g) → C+ (g) + O (g)  | ΔrH°(0 K) = 22.3713 ± 0.0015 eV | Ng 2007 | 0.4 | 1882.12 | CH4 (g) → C (g) + 4 H (g)  | ΔrH°(0 K) = 392.46 ± 0.15 kcal/mol | Karton 2007a | 0.4 | 1901.11 | CH3 (g) → C (g) + 3 H (g)  | ΔrH°(0 K) = 289.08 ± 0.15 kcal/mol | Karton 2008 | 0.3 | 1902.2 | CH3 (g) → C (g) + 3 H (g)  | ΔrH°(0 K) = 1209.48 ± 0.70 kJ/mol | Harding 2008 | 0.2 | 1902.3 | CH3 (g) → C (g) + 3 H (g)  | ΔrH°(0 K) = 1209.48 ± 0.74 kJ/mol | Harding 2008 | 0.2 | 1900.9 | CH3 (g) → C (g) + 3 H (g)  | ΔrH°(0 K) = 1209.93 ± 0.75 kJ/mol | Tajti 2004, est unc | 0.2 | 1902.1 | CH3 (g) → C (g) + 3 H (g)  | ΔrH°(0 K) = 1209.93 ± 0.75 kJ/mol | Tajti 2004, est unc | 0.2 | 1938.8 | CH3 (g) → CH2 (g, triplet) + H (g)  | ΔrH°(0 K) = 457.05 ± 0.56 kJ/mol | Harding 2008 | 0.2 | 2397.1 | CH3OH (g) → CH3 (g) + OH (g)  | ΔrH°(0 K) = 90.12 ± 0.17 kcal/mol | Nguyen 2015a | 0.2 | 1764.7 | C (graphite) + O2 (g) → CO2 (g)  | ΔrH°(298.15 K) = -393.464 ± 0.024 kJ/mol | Hawtin 1966, note CO2e |
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Top 10 species with enthalpies of formation correlated to the ΔfH° of CH4 (g) |
Please note: The correlation coefficients are obtained by renormalizing the off-diagonal elements of the covariance matrix by the corresponding variances. The correlation coefficient is a number from -1 to 1, with 1 representing perfectly correlated species, -1 representing perfectly anti-correlated species, and 0 representing perfectly uncorrelated species.
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Correlation Coefficent (%) | Species Name | Formula | Image | ΔfH°(0 K) | ΔfH°(298.15 K) | Uncertainty | Units | Relative Molecular Mass | ATcT ID | 97.4 | Methylium | [CH3]+ (g) | | 1099.340 | 1095.396 | ± 0.056 | kJ/mol | 15.03397 ± 0.00083 | 14531-53-4*0 | 89.4 | Methyl | CH3 (g) | | 149.872 | 146.458 | ± 0.059 | kJ/mol | 15.03452 ± 0.00083 | 2229-07-4*0 | 83.4 | Methane cation | [CH4]+ (g) | | 1150.673 | 1144.290 | ± 0.066 | kJ/mol | 16.04191 ± 0.00085 | 20741-88-2*0 | 30.7 | Iodomethane | CH3I (g) | | 24.50 | 14.97 | ± 0.18 | kJ/mol | 141.93899 ± 0.00083 | 74-88-4*0 | 30.7 | Methyl iodide cation | [CH3I]+ (g) | | 944.79 | 935.40 | ± 0.18 | kJ/mol | 141.93844 ± 0.00083 | 12538-72-6*0 | 28.3 | Bromomethane | CH3Br (g) | | -20.88 | -36.28 | ± 0.18 | kJ/mol | 94.9385 ± 0.0013 | 74-83-9*0 | 27.7 | Iodomethane | CH3I (l) | | | -12.18 | ± 0.20 | kJ/mol | 141.93899 ± 0.00083 | 74-88-4*590 | 27.3 | Methyl bromide cation | [CH3Br]+ (g) | | 996.24 | 981.32 | ± 0.18 | kJ/mol | 94.9380 ± 0.0013 | 12538-70-4*0 | 26.7 | Bromomethane | CH3Br (l) | | -56.60 | -59.61 | ± 0.19 | kJ/mol | 94.9385 ± 0.0013 | 74-83-9*590 | 25.4 | Carbon atom | C (g) | | 711.399 | 716.885 | ± 0.047 | kJ/mol | 12.01070 ± 0.00080 | 7440-44-0*0 |
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Most Influential reactions involving CH4 (g)Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.
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Influence Coefficient | TN ID | Reaction | Measured Quantity | Reference | 0.988 | 1883.1 | CH4 (g) → [CH4]+ (g)  | ΔrH°(0 K) = 101752.2 ± 3.0 cm-1 | Worner 2007, note unc | 0.959 | 1909.1 | CH4 (g) → [CH3]+ (g) + H (g)  | ΔrH°(0 K) = 14.32271 ± 0.00013 eV | Chang 2017 | 0.726 | 1885.3 | [CH4]- (g) → CH4 (g)  | ΔrH°(0 K) = -0.997 ± 0.061 eV | Ruscic G4 | 0.632 | 1888.1 | 2 H2 (g) + C (graphite) → CH4 (g)  | ΔrG°(1165 K) = 37.521 ± 0.068 kJ/mol | Smith 1946, note COf, 3rd Law | 0.283 | 4700.11 | CH2CHF (g) + CH4 (g) → CH2CH2 (g) + CH3F (g)  | ΔrH°(0 K) = 8.36 ± 0.20 kcal/mol | Karton 2011 | 0.280 | 4738.2 | HCCH (g) + 2 CH3Br (g) → BrCCBr (g) + 2 CH4 (g)  | ΔrH°(0 K) = 2.34 ± 1.0 kcal/mol | Ruscic G4 | 0.263 | 4744.12 | HCCF (g) + CH3F (g) → FCCF (g) + CH4 (g)  | ΔrH°(0 K) = 14.03 ± 0.20 kcal/mol | Karton 2011 | 0.253 | 1895.5 | [CH5]+ (g) + CO2 (g) → [HOCO]+ (g) + CH4 (g)  | ΔrG°(296 K) = 7.92 ± 0.20 kJ/mol | Bohme 1973a, 3rd Law, note unc | 0.231 | 4738.1 | HCCH (g) + 2 CH3Br (g) → BrCCBr (g) + 2 CH4 (g)  | ΔrH°(0 K) = 3.37 ± 1.1 kcal/mol | Ruscic G3X | 0.230 | 4743.12 | HCCH (g) + CH3F (g) → HCCF (g) + CH4 (g)  | ΔrH°(0 K) = 8.81 ± 0.20 kcal/mol | Karton 2011 | 0.229 | 1895.7 | [CH5]+ (g) + CO2 (g) → [HOCO]+ (g) + CH4 (g)  | ΔrG°(296 K) = 7.82 ± 0.21 kJ/mol | Hemsworth 1973, 3rd Law, note unc | 0.218 | 2165.8 | CH2NH2 (g) + CH4 (g) → CH3NH2 (g) + CH3 (g)  | ΔrH°(0 K) = 12.19 ± 0.20 kcal/mol | Karton 2011 | 0.209 | 1895.6 | [CH5]+ (g) + CO2 (g) → [HOCO]+ (g) + CH4 (g)  | ΔrG°(296 K) = 7.72 ± 0.22 kJ/mol | Bohme 1973a, 3rd Law, note unc | 0.208 | 4335.7 | 4 CH3F (g) → CF4 (g) + 3 CH4 (g)  | ΔrH°(0 K) = -218.8 ± 2.0 kJ/mol | Klopper 2010a, est unc | 0.192 | 4665.11 | CH3CH2F (g) + CH4 (g) → CH3F (g) + CH3CH3 (g)  | ΔrH°(0 K) = 6.78 ± 0.20 kcal/mol | Karton 2011 | 0.182 | 1885.4 | [CH4]- (g) → CH4 (g)  | ΔrH°(0 K) = -0.852 ± 0.092 (×1.325) eV | Ruscic CBS-n | 0.175 | 4544.1 | CH4 (g) + CBr4 (g) → 2 CH2Br2 (g)  | ΔrH°(0 K) = -3.64 ± 1.2 kcal/mol | Ruscic G3B3 | 0.175 | 4544.2 | CH4 (g) + CBr4 (g) → 2 CH2Br2 (g)  | ΔrH°(0 K) = -3.35 ± 1.2 kcal/mol | Ruscic G3 | 0.173 | 4238.4 | 2 CCl3CCl3 (g) + 3 CH4 (g) → 3 CCl4 (g) + 2 CH3CH3 (g)  | ΔrH°(0 K) = 17.46 ± 1.50 kcal/mol | Ruscic W1RO | 0.171 | 2321.9 | FCN (g) + CH4 (g) → HCN (g) + CH3F (g)  | ΔrH°(0 K) = -40.3 ± 1.7 kJ/mol | Klopper 2010a |
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References
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1
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B. Ruscic, R. E. Pinzon, M. L. Morton, G. von Laszewski, S. Bittner, S. G. Nijsure, K. A. Amin, M. Minkoff, and A. F. Wagner,
Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited.
J. Phys. Chem. A 108, 9979-9997 (2004)
[DOI: 10.1021/jp047912y]
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2
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B. Ruscic, R. E. Pinzon, G. von Laszewski, D. Kodeboyina, A. Burcat, D. Leahy, D. Montoya, and A. F. Wagner,
Active Thermochemical Tables: Thermochemistry for the 21st Century.
J. Phys. Conf. Ser. 16, 561-570 (2005)
[DOI: 10.1088/1742-6596/16/1/078]
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3
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B. Ruscic and D. H. Bross, Active Thermochemical Tables (ATcT) values based on ver. 1.122h of the Thermochemical Network (2020); available at ATcT.anl.gov |
4
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J. P. Porterfield, D. H. Bross, B. Ruscic, J. H. Thorpe, T. L. Nguyen, J. H. Baraban, J. F. Stanton, J. W. Daily, and G. B. Ellison,
Thermal Decomposition of Potential Ester Biofuels, Part I: Methyl Acetate and Methyl Butanoate.
J. Chem. Phys. A 121, 4658-4677 (2017)
[DOI: 10.1021/acs.jpca.7b02639] (Veronica Vaida Festschrift)
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5
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Y.-C. Chang, B. Xiong, D. H. Bross, B. Ruscic, and C. Y. Ng,
A Vacuum Ultraviolet laser Pulsed Field Ionization-Photoion Study of Methane (CH4): Determination of the Appearance Energy of Methylium From Methane with Unprecedented Precision and the Resulting Impact on the Bond Dissociation Energies of CH4 and CH4+.
Phys. Chem. Chem. Phys. 19, 9592-9605 (2017)
[DOI: 10.1039/c6cp08200a] (part of 2017 PCCP Hot Articles collection)
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6
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B. Ruscic,
Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables.
Int. J. Quantum Chem. 114, 1097-1101 (2014)
[DOI: 10.1002/qua.24605]
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Formula
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The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.
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Uncertainties
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The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [6]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.0005 kJ/mol.
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Website Functionality Credits
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The reorganization of the website was developed and implemented by David H. Bross (ANL).
The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN.
The molecule images are rendered by Indigo-depict.
The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/.
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Acknowledgement
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This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. DE-AC02-06CH11357.
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