Selected ATcT [1, 2] enthalpy of formation based on version 1.130 of the Thermochemical Network [3]

This version of ATcT results[4] was generated by additional expansion of version 1.128 [5,6] to include with the calculations provided in reference [4].

Urea

Formula: NH2C(O)NH2 (cr,l)

CAS RN: 57-13-6

ATcT ID: 57-13-6*500

SMILES: NC(=O)N

InChI: InChI=1S/CH4N2O/c2-1(3)4/h(H4,2,3,4)

InChIKey: XSQUKJJJFZCRTK-UHFFFAOYSA-N

Hills Formula: C1H4N2O1

2D Image:

Aliases: NH2C(O)NH2; Urea; Carbamide; Carbamimidic acid; Carbonyl diamide; Carbonyl diamine; Carbamoylamine

Relative Molecular Mass: 60.05534 ± 0.00091

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
-317.73	-333.33	± 0.12	kJ/mol

Top contributors to the provenance of Δ_fH° of NH2C(O)NH2 (cr,l)

The 7 contributors listed below account for 90.3% of the provenance of Δ_fH° of NH2C(O)NH2 (cr,l).

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
39.1	7378.3	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(301.15 K) = -631.52 ± 0.16 kJ/mol	Contineanu 1982, Johnson 1975
35.7	7378.6	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -150.99 ± 0.04 kcal/mol	Huffman 1940
6.5	7378.5	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -150.90 ± 0.05 (×1.874) kcal/mol	Mansson 1963, as quoted by Cox 1970, note unc
3.9	121.2	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
2.2	7378.1	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -632.06 ± 0.67 kJ/mol	Kabo 1990, Simirsky 1987
1.4	2279.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
1.3	2277.7	CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -890.578 ± 0.078 kJ/mol	Schley 2010

Top 10 species with enthalpies of formation correlated to the Δ_fH° of NH2C(O)NH2 (cr,l)

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
36.1	Water	H2O (cr,l)	-286.272	-285.800	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*500
36.1	Water	H2O (g, ortho)	-238.617	-241.805	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*1
36.1	Water	H2O (g, para)	-238.902	-241.805	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*2
36.1	Water	H2O (g)	-238.902	-241.805	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*0
36.1	Water	H2O (cr, l, eq.press.)	-286.274	-285.801	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*499
36.1	Water	H2O (l, eq.press.)		-285.801	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*589
36.1	Oxonium	[H3O]+ (aq)		-285.800	± 0.022	kJ/mol	19.02267 ± 0.00037	13968-08-6*800
36.1	Water	H2O (l)		-285.800	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*590
36.1	Water	H2O (cr)	-286.272	-292.712	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*510
36.1	Water	H2O (cr, eq.press.)	-286.274	-292.714	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*509

Most Influential reactions involving NH2C(O)NH2 (cr,l)

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
0.463	7379.3	NH2C(O)NH2 (cr,l) → NH2C(O)NH2 (g)	Δ_rH°(351.3 K) = 96.9 ± 0.6 kJ/mol	de Wit 1983a, est unc
0.459	7378.3	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(301.15 K) = -631.52 ± 0.16 kJ/mol	Contineanu 1982, Johnson 1975
0.419	7378.6	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -150.99 ± 0.04 kcal/mol	Huffman 1940
0.166	7379.1	NH2C(O)NH2 (cr,l) → NH2C(O)NH2 (g)	Δ_rH°(366 K) = 97.6 ± 1.0 kJ/mol	Kabo 1990
0.076	7378.5	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -150.90 ± 0.05 (×1.874) kcal/mol	Mansson 1963, as quoted by Cox 1970, note unc
0.041	7379.2	NH2C(O)NH2 (cr,l) → NH2C(O)NH2 (g)	Δ_rH°(350 K) = 97.1 ± 2.0 kJ/mol	Zaitsau 2003, Emelyanenko 2006, est unc
0.026	7378.1	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -632.06 ± 0.67 kJ/mol	Kabo 1990, Simirsky 1987
0.002	7378.4	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -151.50 ± 0.40 (×1.297) kcal/mol	Sunner 1946, as quoted by Cox 1970
0.000	7378.2	NH2C(O)NH2 (cr,l) + 3/2 O2 (g) → 2 H2O (cr,l) + CO2 (g) + N2 (g)	Δ_rH°(298.15 K) = -645.0 ± 2.0 (×6.727) kJ/mol	Contineanu 1982, Johnson 1975, note unc5

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. 1.130 of the Thermochemical Network. Argonne National Laboratory, Lemont, Illinois 2023; available at ATcT.anl.gov [DOI: 10.17038/CSE/1997229]
4		N. Genossar, P. B. Changala, B. Gans, J.-C. Loison, S. Hartweg, M.-A. Martin-Drumel, G. A. Garcia, J. F. Stanton, B. Ruscic, and J. H. Baraban Ring-Opening Dynamics of the Cyclopropyl Radical and Cation: the Transition State Nature of the Cyclopropyl Cation J. Am. Chem. Soc. 144, 18518-18525 (2022) [DOI: 10.1021/jacs.2c07740]
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		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]
8		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 [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.