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].

Nitrous acid

Formula: HONO (g)

CAS RN: 7782-77-6

ATcT ID: 7782-77-6*0

SMILES: N(=O)O

InChI: InChI=1S/HNO2/c2-1-3/h(H,2,3)

InChIKey: IOVCWXUNBOPUCH-UHFFFAOYSA-N

Hills Formula: H1N1O2

2D Image:

Aliases: HONO; Nitrous acid; Nytrosyl hydroxide; ONOH; HO-N=O; O=N-OH

Relative Molecular Mass: 47.01348 ± 0.00061

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
-72.987	-78.644	± 0.077	kJ/mol

3D Image of HONO (g)

spin ON spin OFF

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

The 20 contributors listed below account only for 81.2% of the provenance of Δ_fH° of HONO (g).
A total of 50 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
20.7	1999.8	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -1.44 ± 0.10 kJ/mol	Vosper 1976, 3rd Law
15.3	1483.2	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 52400 ± 10 cm-1	Dingle 1975
15.3	1483.1	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 52400 ± 10 cm-1	Callear 1970
11.2	1483.4	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 52408 ± 10 (×1.164) cm-1	Kley 1973, Miescher 1974, est unc
3.3	1999.2	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -1.25 ± 0.25 kJ/mol	Wayne 1951, 3rd Law
2.6	1483.3	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 52420 ± 12 (×2) cm-1	Miescher 1974, Huber 1979
2.0	2000.3	ONN(O)O (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -3.26 ± 0.15 (×2.044) kJ/mol	Vosper 1976, 3rd Law
1.6	1436.3	N2 (g) → N+ (g) + N (g)	Δ_rH°(0 K) = 24.2880 ± 0.0009 eV	Tang 2005
1.3	1436.1	N2 (g) → N+ (g) + N (g)	Δ_rH°(0 K) = 24.2888 ± 0.0010 eV	Tang 2005
1.3	1436.2	N2 (g) → N+ (g) + N (g)	Δ_rH°(0 K) = 24.2883 ± 0.0010 eV	Tang 2005
1.0	1725.3	(NH4)NO3 (cr,l) → N2 (g) + 1/2 O2 (g) + 2 H2O (cr,l)	Δ_rH°(293.65 K) = -49.44 ± 0.06 kcal/mol	Becker 1934
0.7	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
0.6	1486.4	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 626.47 ± 0.56 kJ/mol	Harding 2008
0.6	2002.1	HONO (g, trans) → OH (g) + NO (g)	Δ_rH°(0 K) = 16772 ± 14 (×1.509) cm-1	Reiche 2000, Reiche 2002, Dieke 1962
0.5	1485.10	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 149.82 ± 0.15 kcal/mol	Karton 2007a, Karton 2008
0.5	1413.11	N2 (g) → 2 N (g)	Δ_rH°(0 K) = 941.14 ± 0.15 kJ/mol	Thorpe 2021
0.5	1483.6	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 6.503 ± 0.004 (×1.682) eV	Brewer 1956, Frisch 1965
0.4	1484.10	NO (g) → N (g) + O (g)	Δ_rH°(0 K) = 149.78 ± 0.16 kcal/mol	Feller 2014
0.4	1952.4	HNO (g) → H (g) + N (g) + O (g)	Δ_rH°(0 K) = 823.10 ± 0.56 kJ/mol	Harding 2008
0.4	1999.4	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(323 K) = 2.57 ± 0.22 (×3.084) kJ/mol	Ashmore 1961, 3rd Law

Top 10 species with enthalpies of formation correlated to the Δ_fH° of HONO (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	Nitrous acid	HONO (g, trans)	-72.987	-79.131	± 0.077	kJ/mol	47.01348 ± 0.00061	7782-77-6*1
82.4	Nitrogen dioxide	ONO (g)	36.866	34.059	± 0.064	kJ/mol	46.00554 ± 0.00060	10102-44-0*0
82.4	Nitric oxide	NO (g)	90.627	91.131	± 0.064	kJ/mol	30.00614 ± 0.00031	10102-43-9*0
82.3	Nitrosyl ion	[NO]+ (g)	984.494	984.489	± 0.064	kJ/mol	30.00559 ± 0.00031	14452-93-8*0
80.1	Dinitrogen tetraoxide	O2NNO2 (g)	20.17	10.88	± 0.14	kJ/mol	92.0111 ± 0.0012	10544-72-6*0
79.5	Nitrosyl chloride	ClNO (g)	54.461	52.559	± 0.067	kJ/mol	65.45884 ± 0.00095	2696-92-6*0
77.6	Dioxohydrazine	ONNO (g, cis)	172.91	171.14	± 0.14	kJ/mol	60.01228 ± 0.00062	16824-89-8*2
77.6	Dioxohydrazine	ONNO (g)	172.91	171.14	± 0.14	kJ/mol	60.01228 ± 0.00062	16824-89-8*0
75.3	Nitrogen sesquioxide	ONN(O)O (g)	90.74	86.17	± 0.15	kJ/mol	76.01168 ± 0.00091	10544-73-7*0
67.6	Nitric oxide	NO (aq, undissoc)		79.218	± 0.078	kJ/mol	30.00614 ± 0.00031	10102-43-9*1000

Most Influential reactions involving HONO (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	1992.1	HONO (g, trans) → HONO (g)	Δ_rH°(0 K) = 0 ± 0 cm-1	Sironneau 2010, Ruscic G3B3
0.710	1999.8	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -1.44 ± 0.10 kJ/mol	Vosper 1976, 3rd Law
0.113	1999.2	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -1.25 ± 0.25 kJ/mol	Wayne 1951, 3rd Law
0.110	2000.3	ONN(O)O (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -3.26 ± 0.15 (×2.044) kJ/mol	Vosper 1976, 3rd Law
0.015	1999.4	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(323 K) = 2.57 ± 0.22 (×3.084) kJ/mol	Ashmore 1961, 3rd Law
0.014	1999.1	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -1.33 ± 0.69 kJ/mol	Wayne 1951, 3rd Law
0.014	1999.6	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(296 K) = -0.97 ± 0.39 (×1.795) kJ/mol	Waldorf 1963, 3rd Law
0.012	1999.3	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rG°(298.15 K) = -1.17 ± 0.75 kJ/mol	Karavaev 1962, Wayne 1951, 3rd Law
0.003	1999.9	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rH°(298.15 K) = -39.3 ± 0.9 (×1.542) kJ/mol	Vosper 1976, 2nd Law
0.002	2000.1	ONN(O)O (g) + H2O (g) → 2 HONO (g)	Δ_rH°(0 K) = 1.05 ± 0.30 (×1.756) kcal/mol	Varma 1976
0.001	1999.7	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rH°(298.15 K) = -9.55 ± 0.5 kcal/mol	Waldorf 1963, 2nd Law, est unc
0.000	2000.2	ONN(O)O (g) + H2O (g) → 2 HONO (g)	Δ_rH°(298.15 K) = 1.9 ± 1.2 (×2.954) kJ/mol	Vosper 1976, 2nd Law
0.000	1999.5	NO (g) + ONO (g) + H2O (g) → 2 HONO (g)	Δ_rH°(323 K) = -37.77 ± 0.65 (×4.757) kJ/mol	Ashmore 1961, 2nd 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. 1.172 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.