Selected ATcT [1, 2] enthalpy of formation based on version 1.176 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.172 to include species related to Criegee intermediates that are involved in several ongoing studies[4].

Methane

Formula: CH4 (aq, undissoc)

CAS RN: 74-82-8

ATcT ID: 74-82-8*1000

SMILES: C

InChI: InChI=1S/CH4/h1H4

InChIKey: VNWKTOKETHGBQD-UHFFFAOYSA-N

Hills Formula: C1H4

2D Image:

Aliases: CH4; Methane; Methyl hydride; Marsh gas

Relative Molecular Mass: 16.04246 ± 0.00085

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
	-87.699	± 0.061	kJ/mol

Top contributors to the provenance of Δ_fH° of CH4 (aq, undissoc)

The 20 contributors listed below account only for 80.3% of the provenance of Δ_fH° of CH4 (aq, undissoc).
A total of 131 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.

Contribution (%)	TN ID	Reaction	Measured Quantity	Reference
36.7	2376.1	CH4 (g) → CH4 (aq, undissoc)	Δ_rG°(298.15 K) = 16.300 ± 0.05 kJ/mol	Clever 1987
19.9	2375.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
9.1	2376.7	CH4 (g) → CH4 (aq, undissoc)	Δ_rG°(298.15 K) = 16.303 ± 0.10 kJ/mol	Warneck 2012, est unc
3.5	2373.7	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.578 ± 0.078 kJ/mol	Schley 2010
2.9	125.2	1/2 O2 (g) + H2 (g) → H2O (cr,l)	Δ_rH°(298.15 K) = -285.8261 ± 0.040 kJ/mol	Rossini 1939, Rossini 1931, Rossini 1931b, note H2Oa, Rossini 1930
2.2	2376.8	CH4 (g) → CH4 (aq, undissoc)	Δ_rH°(298.15 K) = -13.045 ± 0.20 kJ/mol	Warneck 2012, Sander 2023, est unc
1.0	2376.2	CH4 (g) → CH4 (aq, undissoc)	Δ_rH°(298.15 K) = -13.189 ± 0.30 kJ/mol	Clever 1987
0.5	2228.7	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.464 ± 0.024 kJ/mol	Hawtin 1966, note CO2e
0.5	2376.5	CH4 (g) → CH4 (aq, undissoc)	Δ_rG°(298.15 K) = 16.39 ± 0.40 kJ/mol	NBS Tables 1989
0.5	2268.11	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 1071.92 ± 0.10 kJ/mol	Thorpe 2021
0.4	2373.4	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.61 ± 0.21 kJ/mol	Dale 2002
0.3	2286.9	C (graphite) + CO2 (g) → 2 CO (g)	Δ_rG°(1165 K) = -33.545 ± 0.058 kJ/mol	Smith 1946, note COf, 3rd Law
0.3	2373.6	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.44 ± 0.26 kJ/mol	GOMB Ref Calorimeter, Alexandrov 2002
0.3	2373.8	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.482 ± 0.260 kJ/mol	Haloua 2015
0.2	2278.2	CO (g) → C+ (g) + O (g)	Δ_rH°(0 K) = 22.3713 ± 0.0015 eV	Ng 2007
0.2	2228.5	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.468 ± 0.038 kJ/mol	Fraser 1952, note CO2f
0.2	2228.4	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.462 ± 0.038 kJ/mol	Lewis 1965, note CO2d
0.2	2388.12	CH3 (g) → C (g) + 3 H (g)	Δ_rH°(0 K) = 289.11 ± 0.10 kcal/mol	Feller 2016, note unc2
0.2	115.11	H2O (g) → O (g) + 2 H (g)	Δ_rH°(0 K) = 917.80 ± 0.15 kJ/mol	Thorpe 2021
0.1	157.1	OH (g) → [OH]+ (g)	Δ_rH°(0 K) = 104989 ± 5 (×2.378) cm-1	Wiedmann 1992, note unc

Top 10 species with enthalpies of formation correlated to the Δ_fH° of CH4 (aq, undissoc)

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.

Correlation Coefficent (%)	Species Name	Formula	Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units	Relative Molecular Mass	ATcT ID
70.7	Methane	CH4 (g)	-66.547	-74.516	± 0.043	kJ/mol	16.04246 ± 0.00085	74-82-8*0
68.0	Methylium	[CH3]+ (g)	1099.349	1095.405	± 0.045	kJ/mol	15.03397 ± 0.00083	14531-53-4*0
60.2	Methyl	CH3 (g)	149.876	146.476	± 0.049	kJ/mol	15.03452 ± 0.00083	2229-07-4*0
54.4	Methane cation	[CH4]+ (g)	1150.683	1144.300	± 0.057	kJ/mol	16.04191 ± 0.00085	20741-88-2*0
32.1	Carbonic acid	C(O)(OH)2 (aq, undissoc)		-698.673	± 0.028	kJ/mol	62.0248 ± 0.0012	463-79-6*1000
31.7	Water	H2O (l, eq.press.)		-285.806	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*589
31.7	Water	H2O (l)		-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*590
31.7	Oxonium	[H3O]+ (aq)		-285.804	± 0.022	kJ/mol	19.02267 ± 0.00037	13968-08-6*800
31.7	Water	H2O (cr,l)	-286.276	-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*500
31.7	Water	H2O (cr, l, eq.press.)	-286.278	-285.806	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*499

Most Influential reactions involving CH4 (aq, undissoc)

Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.

Influence Coefficient	TN ID	Reaction	Measured Quantity	Reference
0.736	2376.1	CH4 (g) → CH4 (aq, undissoc)	Δ_rG°(298.15 K) = 16.300 ± 0.05 kJ/mol	Clever 1987
0.184	2376.7	CH4 (g) → CH4 (aq, undissoc)	Δ_rG°(298.15 K) = 16.303 ± 0.10 kJ/mol	Warneck 2012, est unc
0.046	2376.8	CH4 (g) → CH4 (aq, undissoc)	Δ_rH°(298.15 K) = -13.045 ± 0.20 kJ/mol	Warneck 2012, Sander 2023, est unc
0.020	2376.2	CH4 (g) → CH4 (aq, undissoc)	Δ_rH°(298.15 K) = -13.189 ± 0.30 kJ/mol	Clever 1987
0.011	2376.5	CH4 (g) → CH4 (aq, undissoc)	Δ_rG°(298.15 K) = 16.39 ± 0.40 kJ/mol	NBS Tables 1989
0.001	2376.6	CH4 (g) → CH4 (aq, undissoc)	Δ_rH°(298.15 K) = -14.23 ± 0.40 (×2.65) kJ/mol	NBS Tables 1989

References

1		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]
2		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 21^st Century. J. Phys. Conf. Ser. 16, 561-570 (2005) [DOI: 10.1088/1742-6596/16/1/078]
3		B. Ruscic and D. H. Bross, Active Thermochemical Tables (ATcT) values based on ver. 1.176 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		T. L. Nguyen et al, ongoing studies (2024)
5		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]
6		B. Ruscic and D. H. Bross, Thermochemistry Computer Aided Chem. Eng. 45, 3-114 (2019) [DOI: 10.1016/B978-0-444-64087-1.00001-2]

Formula

The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.

Uncertainties

The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [5] and Ruscic and Bross[6]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.000₅ kJ/mol.

Website Functionality Credits

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/.

Acknowledgement

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.