Selected ATcT [1, 2] enthalpy of formation based on version 1.156 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.148 to include species relevant to a recent study of the oxidation of ethylene [4] as well as new measurements that led to refining the thermochemistry of CF and SiF and their cations [5].

Water

Formula: H2O (g)

CAS RN: 7732-18-5

ATcT ID: 7732-18-5*0

SMILES: O

InChI: InChI=1S/H2O/h1H2

InChIKey: XLYOFNOQVPJJNP-UHFFFAOYSA-N

Hills Formula: H2O1

2D Image:

Aliases: Water; Oxidane; HOH; Dihydrogen oxide; Dihydrogen monoxide; Hydrogen oxide; Oxygen dyhydride; H2O

Relative Molecular Mass: 18.01528 ± 0.00033

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
-238.904	-241.807	± 0.022	kJ/mol

3D Image of H2O (g)

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Top contributors to the provenance of Δ_fH° of H2O (g)

The 20 contributors listed below account only for 65.6% of the provenance of Δ_fH° of H2O (g).
A total of 292 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
29.8	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
8.6	2357.7	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.578 ± 0.078 kJ/mol	Schley 2010
8.3	2359.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
2.1	115.11	H2O (g) → O (g) + 2 H (g)	Δ_rH°(0 K) = 917.80 ± 0.15 kJ/mol	Thorpe 2021
1.9	157.1	OH (g) → [OH]+ (g)	Δ_rH°(0 K) = 104989 ± 5 (×2.327) cm-1	Wiedmann 1992, note unc
1.6	167.6	H2O (g) → [OH]+ (g) + H (g)	Δ_rH°(0 K) = 18.1183 ± 0.0015 (×1.044) eV	Bodi 2014
1.4	152.1	OH (g) → O (g) + H (g)	Δ_rH°(0 K) = 35580 ± 15 cm-1	Sun 2020
1.3	1717.1	N2 (g) + 3 H2O (cr,l) + 2 H+ (aq) → 3/2 O2 (g) + 2 [NH4]+ (aq)	Δ_rH°(298.15 K) = 141.292 ± 0.119 kcal/mol	Vanderzee 1972c
1.2	169.1	[OH]- (g) → O- (g) + H (g)	Δ_rH°(0 K) = 4.7796 ± 0.0010 (×2.044) eV	Martin 2001, est unc
1.1	2357.4	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.61 ± 0.21 kJ/mol	Dale 2002
1.0	167.7	H2O (g) → [OH]+ (g) + H (g)	Δ_rH°(0 K) = 18.1190 ± 0.002 eV	Bodi 2014
0.9	2252.11	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 1071.92 ± 0.10 (×1.242) kJ/mol	Thorpe 2021
0.8	167.5	H2O (g) → [OH]+ (g) + H (g)	Δ_rH°(0 K) = 18.1177 ± 0.0015 (×1.445) eV	Bodi 2014
0.8	175.1	[OH]+ (g) → O+ (g) + H (g)	Δ_rH°(0 K) = 40412.0 ± 2.2 cm-1	Moselhy 1975, note unc
0.7	2357.8	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.482 ± 0.260 kJ/mol	Haloua 2015
0.7	2357.6	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
0.7	2269.3	CO (g) + H2O (g) → CO2 (g) + H2 (g)	Δ_rG°(893 K) = -6.369 ± 0.283 kJ/mol	Meyer 1938, note COi, 3rd Law
0.6	2262.2	CO (g) → C+ (g) + O (g)	Δ_rH°(0 K) = 22.3713 ± 0.0015 eV	Ng 2007
0.5	1528.4	NNO (g) + CO (g) → CO2 (g) + N2 (g)	Δ_rH°(293.15 K) = -365.642 ± 0.243 kJ/mol	Fenning 1933, note N2Oa
0.5	2452.1	CH3CH3 (g) + 7/2 O2 (g) → 2 CO2 (g) + 3 H2O (cr,l)	Δ_rH°(298.15 K) = -1560.68 ± 0.25 (×1.325) kJ/mol	Pittam 1972

Top 10 species with enthalpies of formation correlated to the Δ_fH° of H2O (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.

Correlation Coefficent (%)	Species Name	Formula	Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units	Relative Molecular Mass	ATcT ID
100.0	Water	H2O (g, para)	-238.904	-241.807	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*2
100.0	Oxonium	[H3O]+ (aq)		-285.802	± 0.022	kJ/mol	19.02267 ± 0.00037	13968-08-6*800
100.0	Water	H2O (cr,l)	-286.274	-285.802	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*500
100.0	Water	H2O (cr, l, eq.press.)	-286.276	-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*499
100.0	Water	H2O (l)		-285.802	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*590
100.0	Water	H2O (l, eq.press.)		-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*589
100.0	Water	H2O (g, ortho)	-238.620	-241.807	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*1
99.9	Water	H2O (cr)	-286.274	-292.715	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*510
99.9	Water	H2O (cr, eq.press.)	-286.276	-292.717	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*509
99.8	Hydroxyl	OH (g)	37.276	37.516	± 0.022	kJ/mol	17.00734 ± 0.00031	3352-57-6*0

Most Influential reactions involving H2O (g)

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
1.000	120.1	H2O (g, para) → H2O (g)	Δ_rH°(0 K) = 0. ± 0. cm-1	Tennyson 2001
0.925	3342.1	CH3CHCH2 (g) + [OH]- (g) → [CH2CHCH2]- (g) + H2O (g)	Δ_rG°(300 K) = -0.30 ± 0.03 kcal/mol	Ellison 1996
0.790	141.5	[H2O]- (g) → H2O (g)	Δ_rH°(0 K) = -1.947 ± 0.050 eV	Ruscic W1RO
0.710	1985.8	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -1.44 ± 0.10 kJ/mol	Vosper 1976, 3rd Law
0.699	9410.5	S(O)(OH)2 (g, cis) → H2O (g) + OSO (g)	Δ_rH°(0 K) = -5.27 ± 0.25 kcal/mol	Misiewicz 2020, est unc
0.667	1238.1	BrOBr (g) + H2O (g) → 2 HOBr (g)	Δ_rG°(298.15 K) = 9.70 ± 1.2 kJ/mol	Hassanzadeh 1997, Orlando 1995
0.609	164.3	H2O (g) → OH (g) + H (g)	Δ_rH°(0 K) = 41145.92 ± 0.12 cm-1	Boyarkin 2013
0.597	214.6	(H2O)3 (g) → 3 H2O (g)	Δ_rH°(0 K) = 3855 ± 20 cm-1	Wang 2011, Anderson 2004, Wang 2011a, Samanta 2014
0.521	5181.1	2 CH4 (g) + 2 H2O (g) → CH3OCO (g, syn-staggered) + 9/2 H2 (g)	Δ_rH°(0 K) = 459.60 ± 2.00 kJ/mol	Klippenstein 2017
0.511	4456.1	2 CH4 (g) + H2O (g) → HCC(O)H (g, syn-triplet) + 4 H2 (g)	Δ_rH°(0 K) = 633.00 ± 1.5 kJ/mol	Klippenstein 2017
0.502	117.1	H2O (g) → [H2O]+ (g)	Δ_rH°(0 K) = 101766.3 ± 1.0 cm-1	Lauzin 2015
0.455	2960.7	CH2OH2 (g) → CH2 (g, singlet) + H2O (g)	Δ_rH°(0 K) = 9.01 ± 0.17 kcal/mol	Nguyen 2015a
0.403	2088.6	HOONO (g, trans, perp) + H2O (g) → HONO (g, trans) + HOOH (g)	Δ_rH°(0 K) = 6.93 ± 0.15 kcal/mol	McGrath 2005
0.389	164.2	H2O (g) → OH (g) + H (g)	Δ_rH°(0 K) = 41145.94 ± 0.15 cm-1	Maksyutenko 2006
0.348	117.2	H2O (g) → [H2O]+ (g)	Δ_rH°(0 K) = 101766.8 ± 1.2 cm-1	Merkt 1998
0.348	7694.1	2 CH4 (g) + 2 H2O (g) → OCCO (g) + 6 H2 (g)	Δ_rH°(0 K) = 625.09 ± 2.00 kJ/mol	Klippenstein 2017
0.338	132.5	H2O (l, eq.press.) → H2O (g)	Δ_rG°(298.15 K) = 8.560013 ± 0.000348 kJ/mol	Wagner 2002
0.332	1922.1	NH3 (g) + H2O (g) → HNOH (g, trans) + 3/2 H2 (g)	Δ_rH°(0 K) = 378.46 ± 1.5 kJ/mol	Klippenstein 2017
0.311	135.4	H2O (l, eq.press.) → H2O (g)	Δ_rG°(300 K) = 8.340252 ± 0.000363 kJ/mol	Wagner 2002
0.271	2020.1	2 ONO (g) + 1/2 O2 (g) + H2O (g) → 2 HON(O)O (g)	Δ_rG°(371 K) = -6.04 ± 0.63 kJ/mol	Jones 1943, 3rd Law

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. 1.156 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		N. A. Seifert, B. Ruscic, R. Sivaramakrishnan, and K. Prozument, The C2H4O Isomers in the Oxidation of Ethylene J. Mol. Spectrosc. 398, 111847/1-8 (2023) [DOI: 10.1016/j.jms.2023.111847]
5		U. Jacovella, B. Ruscic, N. L. Chen, H.-L. Le, S. Boyé-Péronne, S. Hartweg, M. Roy-Chowdhury, G. A. Garcia, J.-C. Loison, and B. Gans, Refining Thermochemical Properties of CF, SiF, and Their Cations by Combining Photoelectron Spectroscopy, Quantum Chemical Calculations, and the Active Thermochemical Tables Approach Phys. Chem. Chem. Phys. 25, 30838-30847 (2023) [DOI: 10.1039/D3CP04244H]
6		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]
7		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 [6] and Ruscic and Bross[7]).
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.