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].

Formaldehyde

Formula: CH2O (aq, unhydrol)

CAS RN: 50-00-0

ATcT ID: 50-00-0*1000

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
	-165.65	± 0.22	kJ/mol

Top contributors to the provenance of Δ_fH° of CH2O (aq, unhydrol)

The 16 contributors listed below account for 90.1% of the provenance of Δ_fH° of CH2O (aq, unhydrol).

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
69.1	3039.3	CH2O (g) → CH2O (aq, unhydrol)	Δ_rG°(298.15 K) = -19.98 ± 0.21 kJ/mol	Warneck 2012, Betterton 1988, Zhou 1990, 3rd Law
9.0	3039.5	CH2O (g) → CH2O (aq, unhydrol)	Δ_rG°(293 K) = -20.79 ± 0.58 kJ/mol	Allou 2011, 3rd Law
3.8	3098.11	[HCO]+ (g) → H+ (g) + CO (g)	Δ_rH°(0 K) = 586.51 ± 0.2 kJ/mol	Czako 2008
1.9	3026.3	CO (g) + H2 (g) → CH2O (g)	Δ_rH°(0 K) = 8.39 ± 0.28 kJ/mol	Czako 2009
1.1	3039.4	CH2O (g) → CH2O (aq, unhydrol)	Δ_rH°(298.15 K) = -56.4 ± 1.6 kJ/mol	Warneck 2012, Betterton 1988, Zhou 1990, 2nd Law
0.7	3039.7	CH2O (g) → CH2O (aq, unhydrol)	Δ_rG°(293 K) = -20.6 ± 2 kJ/mol	Staudinger 1996, 3rd Law, est unc, Allou 2011
0.5	3100.9	CO (g) + [NH4]+ (g) → [HCO]+ (g) + NH3 (g)	Δ_rH°(0 K) = 259.89 ± 0.3 kJ/mol	Czako 2008
0.5	3025.7	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.44 ± 0.25 kcal/mol	Karton 2006
0.5	3025.8	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.44 ± 0.25 kcal/mol	Karton 2006
0.4	3006.1	[CH2OH]+ (g) → CH2O (g) + H+ (g)	Δ_rH°(0 K) = 704.98 ± 0.39 kJ/mol	Czako 2009
0.4	3091.9	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1132.68 ± 0.56 kJ/mol	Harding 2008
0.3	3025.6	2 CH2O (g) → CH4 (g) + CO2 (g)	Δ_rH°(0 K) = -59.52 ± 0.30 kcal/mol	Karton 2006
0.3	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
0.2	1666.8	[NH4]+ (g) → NH3 (g) + H+ (g)	Δ_rH°(0 K) = 846.40 ± 0.3 kJ/mol	Czako 2008
0.2	3091.7	HCO (g) → H (g) + O (g) + C (g)	Δ_rH°(0 K) = 1133.05 ± 0.70 kJ/mol	Harding 2008
0.2	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

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

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
43.5	Formaldehyde	CH2O (g)	-105.381	-109.222	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*0
43.5	Formaldehyde	CH2O (g, singlet)	-105.381	-109.222	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*2
43.5	Formaldehyde	CH2O (g, para singlet)	-105.381	-109.222	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*21
43.5	Formaldehyde	CH2O (g, ortho singlet)	-105.255	-109.221	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*22
43.5	Formaldehyde	CH2O (g, triplet)	196.009	192.707	± 0.094	kJ/mol	30.02598 ± 0.00087	50-00-0*1
43.3	Formyl	HCO (g)	41.389	41.763	± 0.094	kJ/mol	29.01804 ± 0.00086	2597-44-6*0
43.3	Oxomethylium	[HCO]+ (g)	827.765	827.180	± 0.095	kJ/mol	29.01749 ± 0.00086	17030-74-9*0
42.9	Formaldehyde cation	[CH2O]+ (g)	944.860	941.239	± 0.096	kJ/mol	30.02543 ± 0.00087	54288-05-0*0
9.9	Hydroxymethylene	HCOH (g, trans)	112.70	108.93	± 0.27	kJ/mol	30.02598 ± 0.00087	19710-56-6*1
9.9	Hydroxymethylene	HCOH (g)	112.70	108.95	± 0.27	kJ/mol	30.02598 ± 0.00087	19710-56-6*0

Most Influential reactions involving CH2O (aq, unhydrol)

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
0.854	3039.3	CH2O (g) → CH2O (aq, unhydrol)	Δ_rG°(298.15 K) = -19.98 ± 0.21 kJ/mol	Warneck 2012, Betterton 1988, Zhou 1990, 3rd Law
0.502	3040.1	CH2O (cr, paraformaldehyde) → CH2O (aq, unhydrol)	Δ_rH°(298.15 K) = 2.4 ± 0.5 kcal/mol	Delepine 1942, note CH2O, est unc
0.112	3039.5	CH2O (g) → CH2O (aq, unhydrol)	Δ_rG°(293 K) = -20.79 ± 0.58 kJ/mol	Allou 2011, 3rd Law
0.014	3039.4	CH2O (g) → CH2O (aq, unhydrol)	Δ_rH°(298.15 K) = -56.4 ± 1.6 kJ/mol	Warneck 2012, Betterton 1988, Zhou 1990, 2nd Law
0.009	3039.7	CH2O (g) → CH2O (aq, unhydrol)	Δ_rG°(293 K) = -20.6 ± 2 kJ/mol	Staudinger 1996, 3rd Law, est unc, Allou 2011
0.001	3039.6	CH2O (g) → CH2O (aq, unhydrol)	Δ_rH°(293 K) = -53.4 ± 4.5 kJ/mol	Allou 2011, 2nd Law
0.001	3039.2	CH2O (g) → CH2O (aq, unhydrol)	Δ_rH°(298.15 K) = -14.8 ± 0.2 (×6.583) kcal/mol	Walker 1933, est unc
0.001	3039.1	CH2O (g) → CH2O (aq, unhydrol)	Δ_rH°(298.15 K) = -14.9 ± 0.2 (×7.179) kcal/mol	Delepine 1942, note CH2O, est unc
0.000	3039.8	CH2O (g) → CH2O (aq, unhydrol)	Δ_rH°(293 K) = -56.5 ± 10 kJ/mol	Staudinger 1996, 2nd Law, est unc, Allou 2011

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.