Selected ATcT [1, 2] enthalpy of formation based on version 1.172 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.156 to include species relevant to a study of photodissociation of formamide[4].

Dihydrogen

Formula: H2 (g, para)

CAS RN: 1333-74-0

ATcT ID: 1333-74-0*2

SMILES: [H][H]

InChI: InChI=1S/H2/h1H

InChIKey: UFHFLCQGNIYNRP-UHFFFAOYSA-N

Hills Formula: H2

2D Image:

Aliases: H2; Dihydrogen; Hydrogen molecule; Hydrogen; Molecular hydrogen; Diatomic hydrogen; o-Hydrogen; p-Hydrogen

Relative Molecular Mass: 2.01588 ± 0.00014

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
-0.000	-0.058	± 0.000	kJ/mol

3D Image of H2 (g, para)

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Top contributors to the provenance of Δ_fH° of H2 (g, para)

The 6 contributors listed below account for 91.5% of the provenance of Δ_fH° of H2 (g, para).

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
58.7	68.1	H2 (g, para) → H2 (g)	Δ_rH°(0 K) = 0.0 ± 0.0 cm-1	triv
13.4	66.13	H2 (g) → [H2]+ (g)	Δ_rH°(0 K) = 124417.49113 ± 0.00074 cm-1	Liu 2012, note unc
9.5	70.1	H2 (g, ortho) → [H2]+ (g)	Δ_rH°(0 K) = 124299.00429 ± 0.00071 cm-1	Liu 2009, note unc, Hannemann 2006, Osterwalder 2004, Karr 2008, Korobov 2006, Korobov 2006a, Korobov 2008
5.2	74.1	[H2]+ (g, para) → [H2]+ (g)	Δ_rH°(0 K) = 0. ± 0. cm-1	Moss 1993b
2.9	72.1	H2 (g, para) → [H2]+ (g, para)	Δ_rH°(0 K) = 124417.491098 ± 0.000062 cm-1	Beyer 2019, note unc
1.6	80.1	H (g) → H+ (g)	Δ_rH°(0 K) = 109678.77174307 ± 0.00000020 cm-1	Mohr 2016, Sprecher 2010, note unc, Tiesinga 2021

Top 10 species with enthalpies of formation correlated to the Δ_fH° of H2 (g, para)

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
83.4	Dihydrogen	H2 (g, ortho)	1.417	0.019	± 0.000	kJ/mol	2.01588 ± 0.00014	1333-74-0*1
71.0	Dihydrogen cation	[H2]+ (g, ortho)	1489.060	1488.480	± 0.000	kJ/mol	2.01533 ± 0.00014	12184-90-6*1
66.7	Dihydrogen cation	[H2]+ (g, para)	1488.364	1488.480	± 0.000	kJ/mol	2.01533 ± 0.00014	12184-90-6*2
52.3	Dihydrogen cation	[H2]+ (g)	1488.364	1488.480	± 0.000	kJ/mol	2.01533 ± 0.00014	12184-90-6*0
40.6	Hydron	H+ (g)	1528.084	1530.047	± 0.000	kJ/mol	1.007391 ± 0.000070	12408-02-5*0
11.8	Deuterium hydride cation	[HD]+ (g)	1490.498	1490.587	± 0.000	kJ/mol	3.021493 ± 0.000070	12181-16-7*0
11.6	Hydrogen atom	H (g)	216.034	217.998	± 0.000	kJ/mol	1.007940 ± 0.000070	12385-13-6*0
8.7	Deuterium hydride	HD (g)	0.328	0.319	± 0.000	kJ/mol	3.022042 ± 0.000070	13983-20-5*0
3.4	Hydride	H- (g)	143.264	145.228	± 0.000	kJ/mol	1.008489 ± 0.000070	12184-88-2*0

Most Influential reactions involving H2 (g, para)

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
0.587	68.1	H2 (g, para) → H2 (g)	Δ_rH°(0 K) = 0.0 ± 0.0 cm-1	triv
0.470	72.1	H2 (g, para) → [H2]+ (g, para)	Δ_rH°(0 K) = 124417.491098 ± 0.000062 cm-1	Beyer 2019, note unc
0.206	69.7	H2 (g, para) → H2 (g, ortho)	Δ_rH°(0 K) = 118.486837 ± 0.000222 cm-1	Jennings 1987, note unc
0.206	69.10	H2 (g, para) → H2 (g, ortho)	Δ_rH°(0 K) = 118.4868127 ± 0.0000022 cm-1	Puchalski 2019, note unc
0.206	69.8	H2 (g, para) → H2 (g, ortho)	Δ_rH°(0 K) = 118.48680 ± 0.00022 cm-1	Piszczatowski 2009, note unc
0.206	69.5	H2 (g, para) → H2 (g, ortho)	Δ_rH°(0 K) = 118.487 ± 0.001 cm-1	Schwartz 1987
0.002	69.3	H2 (g, para) → H2 (g, ortho)	Δ_rH°(0 K) = 118.48 ± 0.01 cm-1	Huber 1979, est unc
0.000	69.4	H2 (g, para) → H2 (g, ortho)	Δ_rH°(0 K) = 118.50 ± 0.02 cm-1	Dabrowski 1984, est unc
0.000	69.2	H2 (g, para) → H2 (g, ortho)	Δ_rH°(0 K) = 118.495 ± 0.02 cm-1	Herzberg 1960, est unc
0.000	73.1	H2 (g, para) → [H2]+ (g, ortho)	Δ_rH°(0 K) = 124476.0 ± 0.5 cm-1	Herzberg 1972, est unc

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. 1.172 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		K. L. Caster, N. A. Seifert, B. Ruscic, A. W. Jasper, and K. Prozument, Dynamics of HCN, NHC, and HNCO Formation in the 193 nm Photodissociation of Formamide J. Phys. Chem. A (in press) (2024) [DOI: 10.1021/acs.jpca.4c02232]
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.