Selected ATcT [1, 2] enthalpy of formation based on version 1.124 of the Thermochemical Network [3]

This version of ATcT results was generated by additional expansion of version 1.122x [4] to include additional information relevant to the study of thermophysical and thermochemical properties of CH2 and CH3 using nonrigid rotor anharmonic oscillator (NRRAO) partition functions [5], the development and benchmarking of a state-of-the-art computational approach that aims to reproduce total atomization energies of small molecules within 10–15 cm^-1 [6], as well as the study of the reversible reaction C₂H₃ + H₂ ⇌ C₂H₄ + H ⇌ C₂H₅ [7]

Oxoniumyl ion

Formula: [H2O]+ (g, ortho)

CAS RN: 56583-62-1

ATcT ID: 56583-62-1*1

SMILES: [H][O+][H]

InChI: InChI=1S/H2O/h1H2/q+1

InChIKey: RECVMTHOQWMYFX-UHFFFAOYSA-N

Hills Formula: H2O1+

2D Image:

Aliases: [H2O]+; Oxoniumyl ion; Oxoniumyl cation; Oxoniumyl ion (1+); Water cation; Water ion (1+); mu-Oxodihydrogen cation; mu-Oxodihydrogen ion (1+); HOH+; [HOH]+

Relative Molecular Mass: 18.01473 ± 0.00033

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
978.501	975.597	± 0.026	kJ/mol

3D Image of [H2O]+ (g, ortho)

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Top contributors to the provenance of Δ_fH° of [H2O]+ (g, ortho)

The 20 contributors listed below account only for 65.8% of the provenance of Δ_fH° of [H2O]+ (g, ortho).
A total of 258 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
32.3	120.2	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
5.5	112.1	H2O (g) → [H2O]+ (g)	Δ_rH°(0 K) = 101766.3 ± 1.0 cm-1	Lauzin 2015
3.8	112.2	H2O (g) → [H2O]+ (g)	Δ_rH°(0 K) = 101766.8 ± 1.2 cm-1	Merkt 1998
3.3	2245.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
2.3	2244.4	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.61 ± 0.21 kJ/mol	Dale 2002
2.2	152.1	OH (g) → [OH]+ (g)	Δ_rH°(0 K) = 104989 ± 5 (×2.229) cm-1	Wiedmann 1992, note unc
1.9	161.6	H2O (g) → [OH]+ (g) + H (g)	Δ_rH°(0 K) = 18.1183 ± 0.0015 eV	Bodi 2014
1.6	147.1	OH (g) → O (g) + H (g)	Δ_rH°(0 K) = 35580 ± 15 cm-1	Sun 2020
1.5	2244.6	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
1.5	1668.1	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
1.3	112.4	H2O (g) → [H2O]+ (g)	Δ_rH°(0 K) = 101766 ± 2 cm-1	Tonkyn 1991
1.2	163.1	[OH]- (g) → O- (g) + H (g)	Δ_rH°(0 K) = 4.7796 ± 0.0010 (×2.089) eV	Martin 2001, est unc
1.0	161.7	H2O (g) → [OH]+ (g) + H (g)	Δ_rH°(0 K) = 18.1190 ± 0.002 eV	Bodi 2014
0.9	169.1	[OH]+ (g) → O+ (g) + H (g)	Δ_rH°(0 K) = 40412.0 ± 2.2 cm-1	Moselhy 1975, note unc
0.9	161.5	H2O (g) → [OH]+ (g) + H (g)	Δ_rH°(0 K) = 18.1177 ± 0.0015 (×1.414) eV	Bodi 2014
0.8	2244.1	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(303.15 K) = -889.849 ± 0.350 kJ/mol	Rossini 1931a, Rossini 1931b, Prosen 1945, Rossini 1940, note CH4
0.8	2244.5	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.43 ± 0.35 kJ/mol	Alexandrov 2002a, Alexandrov 2002
0.7	2156.3	CO (g) + H2O (g) → CO2 (g) + H2 (g)	Δ_rG°(893 K) = -6.369 ± 0.283 kJ/mol	Meyer 1938, note COi, 3rd Law
0.7	2149.2	CO (g) → C+ (g) + O (g)	Δ_rH°(0 K) = 22.3713 ± 0.0015 eV	Ng 2007
0.6	2337.1	CH3CH3 (g) + 7/2 O2 (g) → 2 CO2 (g) + 3 H2O (cr,l)	Δ_rH°(298.15 K) = -1560.68 ± 0.25 (×1.445) kJ/mol	Pittam 1972

Top 10 species with enthalpies of formation correlated to the Δ_fH° of [H2O]+ (g, ortho)

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	Oxoniumyl ion	[H2O]+ (g)	978.501	975.597	± 0.026	kJ/mol	18.01473 ± 0.00033	56583-62-1*0
100.0	Oxoniumyl ion	[H2O]+ (g, para)	978.750	975.599	± 0.026	kJ/mol	18.01473 ± 0.00033	56583-62-1*2
94.3	Water	H2O (g)	-238.898	-241.801	± 0.025	kJ/mol	18.01528 ± 0.00033	7732-18-5*0
94.3	Water	H2O (g, para)	-238.898	-241.801	± 0.025	kJ/mol	18.01528 ± 0.00033	7732-18-5*2
94.3	Water	H2O (g, ortho)	-238.613	-241.801	± 0.025	kJ/mol	18.01528 ± 0.00033	7732-18-5*1
94.3	Water	H2O (cr,l)	-286.268	-285.796	± 0.025	kJ/mol	18.01528 ± 0.00033	7732-18-5*500
94.3	Water	H2O (cr, l, eq.press.)	-286.269	-285.797	± 0.025	kJ/mol	18.01528 ± 0.00033	7732-18-5*499
94.3	Water	H2O (l)		-285.796	± 0.025	kJ/mol	18.01528 ± 0.00033	7732-18-5*590
94.3	Water	H2O (l, eq.press.)		-285.797	± 0.025	kJ/mol	18.01528 ± 0.00033	7732-18-5*589
94.3	Oxonium	[H3O]+ (aq)		-285.796	± 0.025	kJ/mol	19.02267 ± 0.00037	13968-08-6*800

Most Influential reactions involving [H2O]+ (g, ortho)

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	119.1	[H2O]+ (g, ortho) → [H2O]+ (g, para)	Δ_rH°(0 K) = 20.857 ± 0.02 cm-1	Lew 1976
1.000	118.1	[H2O]+ (g, ortho) → [H2O]+ (g)	Δ_rH°(0 K) = 0. ± 0. cm-1	Tennyson 2001

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. 1.124 of the Thermochemical Network, Argonne National Laboratory, Lemont, Illinois 2022; available at ATcT.anl.gov [DOI: 10.17038/CSE/1885923]
4		Y. Ren, L. Zhou, A. Mellouki, V. Daële, M. Idir, S. S. Brown, B. Ruscic, Robert S. Paton, M. R. McGillen, and A. R. Ravishankara, Reactions of NO3 with Aromatic Aldehydes: Gas-Phase Kinetics and Insights into the Mechanism of the Reaction. Atmos. Chem. Phys. 21, 13537-13551 (2021) [DOI: 10.5194/acp2021-228]
5		B. Ruscic and D. H. Bross, Active Thermochemical Tables: The Thermophysical and Thermochemical Properties of Methyl, CH3, and Methylene, CH2, Corrected for Nonrigid Rotor and Anharmonic Oscillator Effects. Mol. Phys. e1969046 (2021) [DOI: 10.1080/00268976.2021.1969046]
6		J. H. Thorpe, J. L. Kilburn, D. Feller, P. B. Changala, D. H. Bross, B. Ruscic, and J. F. Stanton, Elaborated Thermochemical Treatment of HF, CO, N2, and H2O: Insight into HEAT and Its Extensions J. Chem. Phys. 155, 184109 (2021) [DOI: 10.1063/5.0069322]
7		T. L. Nguyen, D. H. Bross, B. Ruscic, G. B. Ellison, and J. F. Stanton, Mechanism, Thermochemistry, and Kinetics of the Reversible Reactions: C2H3 + H2 ⇌ C2H4 + H ⇌ C2H5. Faraday Discuss. , (Advance Article) (2022) [DOI: 10.1039/D1FD00124H]
8		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]
9		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 [8,9]).
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.