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].

Formaldehyde

Formula: CH2O (g, singlet)

CAS RN: 50-00-0

ATcT ID: 50-00-0*2

SMILES: C=O

InChI: InChI=1S/CH2O/c1-2/h1H2

InChIKey: WSFSSNUMVMOOMR-UHFFFAOYSA-N

Hills Formula: C1H2O1

2D Image:

Aliases: Formaldehyde; Methanal; Formaldehyde monomer; Methyl aldehyde; Oxymethylene; Oxymethylene monomer; Methylene oxide; H2CO; CH2O; H2CO g; CH2O g; H2C=O

Relative Molecular Mass: 30.02598 ± 0.00087

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
-105.382	-109.223	± 0.094	kJ/mol

3D Image of CH2O (g, singlet)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of CH2O (g, singlet)

The 20 contributors listed below account only for 62.2% of the provenance of Δ_fH° of CH2O (g, singlet).
A total of 274 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
20.0	3098.11	[HCO]+ (g) → H+ (g) + CO (g)	Δ_rH°(0 K) = 586.51 ± 0.2 kJ/mol	Czako 2008
10.3	3026.3	CO (g) + H2 (g) → CH2O (g)	Δ_rH°(0 K) = 8.39 ± 0.28 kJ/mol	Czako 2009
3.0	3100.9	CO (g) + [NH4]+ (g) → [HCO]+ (g) + NH3 (g)	Δ_rH°(0 K) = 259.89 ± 0.3 kJ/mol	Czako 2008
2.9	3025.7	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.44 ± 0.25 kcal/mol	Karton 2006
2.9	3025.8	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.44 ± 0.25 kcal/mol	Karton 2006
2.5	3006.1	[CH2OH]+ (g) → CH2O (g) + H+ (g)	Δ_rH°(0 K) = 704.98 ± 0.39 kJ/mol	Czako 2009
2.3	3091.9	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.68 ± 0.56 kJ/mol	Harding 2008
2.0	3025.6	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.52 ± 0.30 kcal/mol	Karton 2006
1.6	3028.1	CH2O (g) + O2 (g) → CO2 (g) + H2O (cr,l)	Δ_rH°(299.65 K) = -570.69 ± 0.40 (×1.756) kJ/mol	Fletcher 1970, note std dev
1.5	1666.8	[NH4]+ (g) → NH3 (g) + H+ (g)	Δ_rH°(0 K) = 846.40 ± 0.3 kJ/mol	Czako 2008
1.5	3091.7	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1133.05 ± 0.70 kJ/mol	Harding 2008
1.4	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
1.3	3091.8	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.53 ± 0.74 kJ/mol	Harding 2008
1.2	3091.6	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.11 ± 0.75 (×1.022) kJ/mol	Tajti 2004, est unc
1.2	3101.11	HCO (g) → H (g) + CO (g)	Δ_rH°(0 K) = 60.2 ± 0.8 kJ/mol	Marenich 2003
1.1	3017.10	CH2O (g) → C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 1495.36 ± 0.80 kJ/mol	Feller 2018a
1.1	3025.4	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.37 ± 0.40 kcal/mol	Boese 2004
1.1	3025.5	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.52 ± 0.40 kcal/mol	Karton 2006
1.0	3091.12	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.50 ± 0.84 kJ/mol	Harding 2008
1.0	3091.10	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.87 ± 0.84 kJ/mol	Harding 2008

Top 10 species with enthalpies of formation correlated to the Δ_fH° of CH2O (g, singlet)

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	Formaldehyde	CH2O (g)	-105.382	-109.223	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*0
100.0	Formaldehyde	CH2O (g, para singlet)	-105.382	-109.223	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*21
100.0	Formaldehyde	CH2O (g, ortho singlet)	-105.256	-109.222	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*22
100.0	Formaldehyde	CH2O (g, triplet)	196.008	192.706	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*1
99.6	Formyl	HCO (g)	41.388	41.762	± 0.094	kJ/mol	29.01804 ± 0.00086	2597-44-6*0
99.4	Oxomethylium	[HCO]+ (g)	827.763	827.179	± 0.095	kJ/mol	29.01749 ± 0.00086	17030-74-9*0
98.6	Formaldehyde cation	[CH2O]+ (g)	944.859	941.238	± 0.096	kJ/mol	30.02543 ± 0.00087	54288-05-0*0
43.5	Formaldehyde	CH2O (aq, unhydrol)		-165.65	± 0.22	kJ/mol	30.02598 ± 0.00087	50-00-0*1000
22.8	Hydroxymethylene	HCOH (g, trans)	112.70	108.93	± 0.27	kJ/mol	30.02598 ± 0.00087	19710-56-6*1
22.8	Hydroxymethylene	HCOH (g)	112.70	108.95	± 0.27	kJ/mol	30.02598 ± 0.00087	19710-56-6*0

Most Influential reactions involving CH2O (g, singlet)

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	3032.1	CH2O (g, singlet) → CH2O (g)	Δ_rH°(0 K) = 0 ± 0 cm-1	triv, Herzberg 1966, Ruscic W1RO, Ruscic G4
0.999	3035.1	CH2O (g, singlet) → CH2O (g, triplet)	Δ_rH°(0 K) = 25194.28 ± 0.02 cm-1	Raynes 1966, Herzberg 1966, Smith 1962, note unc2
0.144	9794.4	CH2S (g, singlet) + CH3OH (g) → CH3SH (g) + CH2O (g, singlet)	Δ_rH°(0 K) = -12.08 ± 1.2 kcal/mol	Ruscic W1RO
0.123	9794.2	CH2S (g, singlet) + CH3OH (g) → CH3SH (g) + CH2O (g, singlet)	Δ_rH°(0 K) = -11.47 ± 1.3 kcal/mol	Ruscic G4
0.106	9794.1	CH2S (g, singlet) + CH3OH (g) → CH3SH (g) + CH2O (g, singlet)	Δ_rH°(0 K) = -11.32 ± 1.4 kcal/mol	Ruscic G3X
0.081	9794.3	CH2S (g, singlet) + CH3OH (g) → CH3SH (g) + CH2O (g, singlet)	Δ_rH°(0 K) = -11.82 ± 1.6 kcal/mol	Ruscic CBS-n
0.000	4819.4	CH2OO (g) + O2 (g, singlet) → CH2O (g, singlet) + OOO (g)	Δ_rH°(0 K) = -45.01 ± 1.3 (×3.914) kcal/mol	Ruscic CBS-n
0.000	4819.3	CH2OO (g) + O2 (g, singlet) → CH2O (g, singlet) + OOO (g)	Δ_rH°(0 K) = -45.14 ± 1.6 (×3.292) kcal/mol	Ruscic CBS-n
0.000	4819.5	CH2OO (g) + O2 (g, singlet) → CH2O (g, singlet) + OOO (g)	Δ_rH°(0 K) = -45.48 ± 1.2 (×4.655) kcal/mol	Ruscic W1RO
0.000	4819.2	CH2OO (g) + O2 (g, singlet) → CH2O (g, singlet) + OOO (g)	Δ_rH°(0 K) = -45.86 ± 1.3 (×4.655) kcal/mol	Ruscic G4
0.000	4819.1	CH2OO (g) + O2 (g, singlet) → CH2O (g, singlet) + OOO (g)	Δ_rH°(0 K) = -45.99 ± 1.4 (×4.362) kcal/mol	Ruscic G3X
0.000	3035.2	CH2O (g, singlet) → CH2O (g, triplet)	Δ_rH°(0 K) = 25194 ± 1 cm-1	Herzberg 1966, Smith 1962, est unc
0.000	3035.3	CH2O (g, singlet) → CH2O (g, triplet)	Δ_rH°(0 K) = 25200.2 ± 1 (×6.037) cm-1	Robinson 1958, Herzberg 1966, Raynes 1966, est unc
0.000	3035.4	CH2O (g, singlet) → CH2O (g, triplet)	Δ_rH°(0 K) = 25243.0 ± 50 cm-1	Hodges 1958, 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. 1.176 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.