Urea

Formula: CH₄N₂O
Molecular weight: 60.0553
IUPAC Standard InChI: InChI=1S/CH4N2O/c2-1(3)4/h(H4,2,3,4)
IUPAC Standard InChIKey: XSQUKJJJFZCRTK-UHFFFAOYSA-N
CAS Registry Number: 57-13-6
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
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Other names: Carbamide; Carbamimidic acid; Carbonyldiamide; Isourea; Pseudourea; Urea-13C; Ureaphil; Ureophil; Urevert; UR; (NH2)2CO; Carbonyl Diamine; Alphadrate; Aquacare; Aquadrate; B-I-K; Calmurid; Carbaderm; Keratinamin; NCI-C02119; Pastaron; Prespersion, 75 urea; Ultra Mide; Urepearl; Mocovina; Supercel 3000; Varioform II; Benural 70; Harnstoff; Basodexan; Bubber shet; Elaqua xx; Hyanit; Nutraplus; Onychomal; NSC 34375; Uroderm; Panafil (Salt/Mix); Cerovel (Salt/Mix); component of Artra Ashy Skin Cream (Salt/Mix)
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- X-ray Photoelectron Spectroscopy Database, version 5.0
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Condensed phase thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_solid	-333.11 ± 0.69	kJ/mol	Ccb	Kabo, Miroshnichenko, et al., 1990	see Simirsky, Kabo, et al., 1987; ALS
Δ_fH°_solid	-320.2 ± 2.0	kJ/mol	Ccb	Contineanu, Wagner, et al., 1982	ALS
Δ_fH°_solid	-333.39 ± 0.17	kJ/mol	Ccb	Johnson, 1975	ALS
Δ_fH°_solid	-333.3 ± 0.2	kJ/mol	Ccb	Huffman, 1940	ALS
Δ_fH°_solid	-323.6	kJ/mol	Ccb	Schmidt and Becker, 1933	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_solid	-635. ± 8.	kJ/mol	AVG	N/A	Average of 8 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
S°_{solid,1 bar}	104.26	J/mol*K	N/A	Andersson, Matsuo, et al., 1993	DH
S°_{solid,1 bar}	104.93	J/mol*K	N/A	Kozyro, Dalidovich, et al., 1986	DH
S°_{solid,1 bar}	105.4	J/mol*K	N/A	Parks, Huffman, et al., 1933	Extrapolation below 90 K, 33.18 J/mol*K.; DH
S°_{solid,1 bar}	172.	J/mol*K	N/A	Gibson, Latimer, et al., 1920	Extrapolation below 86 K, no details.; DH

Constant pressure heat capacity of solid

C_p,solid (J/mol*K)	Temperature (K)	Reference	Comment
92.79	298.15	Andersson, Matsuo, et al., 1993	T = 15 to 310 K.; DH
94.0	304.7	Gambino and Bros, 1988	T = 303 to 413 K.; DH
93.08	298.15	Kozyro, Dalidovich, et al., 1986	T = 5 to 400 K. Cp = 38.43 + 4.98x10-2T + 7.05x10-4T2 - 8.61x10-7T3 (240 to 400 K).; DH
90.0	298.15	Sasaki and Yokotake, 1966	T = 90 to 298 K.; DH
93.14	298.15	Ruehrwein and Huffman, 1946	T = 19 to 318 K.; DH
68.6	293.	Campbell and Campbell, 1940	DH
93.64	298.0	Parks, Huffman, et al., 1933	T = 93 to 298 K. Value is unsmoothed experimental datum.; DH
115.5	298.0	Gibson, Latimer, et al., 1920	T = 86 to 300 K. Value is unsmoothed experimental datum.; DH

IR Spectrum

Go To: Top, Condensed phase thermochemistry data, References, Notes

Data compiled by: Coblentz Society, Inc.

SOLID (SPLIT MULL, FLUOROLUBE FOR 3800-1333 AND NUJOL FOR 1333-450 CM ^-1); DOW KBr FOREPRISM-GRATING; DIGITIZED BY NIST FROM HARD COPY (FROM TWO SEGMENTS); 4 cm^-1 resolution

Data compiled by: Timothy J. Johnson, Tanya L. Myers, Yin-Fong Su, Russell G. Tonkyn, Molly Rose K. Kelly-Gorham, and Tyler O. Danby

solid; Bruker Tensor 37 FTIR; 0.96450084 cm^-1 resolution

References

Go To: Top, Condensed phase thermochemistry data, IR Spectrum, Notes

Kabo, Miroshnichenko, et al., 1990
Kabo, G.Ya.; Miroshnichenko, E.A.; Frenkel, M.L.; Kozyro, A.A.; Simirskii, V.V.; Krasulin, A.P.; Vorob'eva, V.P.; Lebedev, Yu.A., Thermochemistry of urea alkyl derivatives, Bull. Acad. Sci. USSR, Div. Chem. Sci., 1990, 662-667. [all data]

Simirsky, Kabo, et al., 1987
Simirsky, V.V.; Kabo, G.J.; Frenkel, M.L., Additivity of the enthalpies of formation of urea derivatives in the crystalline state, J. Chem. Thermodyn., 1987, 19, 1121-1127. [all data]

Contineanu, Wagner, et al., 1982
Contineanu, I.; Wagner, L.; Stanescu, L.; Marchidan, D.I., Combustion and formation enthalpies of o-phenylenediamine, urea and 2-benzimidazolone, Rev. Roum. Chim., 1982, 27, 205-209. [all data]

Johnson, 1975
Johnson, W.H., The enthalpies of combustion and formation of acetanilide and urea, J. Res. NBS, 1975, 79, 487-491. [all data]

Huffman, 1940
Huffman, H.M., Thermal Data. XII. The heats of combustion of urea and guanidine carbonate and their standard free energies of formation, J. Am. Chem. Soc., 1940, 62, 1009-1011. [all data]

Schmidt and Becker, 1933
Schmidt, V.A.; Becker, F., Die Bildungswarme von Nitrocellulofen, Nitroglycerin und anderen widuigen Beltandteilen von Treibmitteln, Z. Gesamte Schiess Sprengstoffwes., 1933, 33, 280-282. [all data]

Andersson, Matsuo, et al., 1993
Andersson, O.; Matsuo, T.; Suga, H.; Ferloni, P., Low-temperature heat capacity of urea, Int. J. Thermophys., 1993, 14(1), 149-158. [all data]

Kozyro, Dalidovich, et al., 1986
Kozyro, A.A.; Dalidovich, S.V.; Krasulin, A.P., Heat capacity, enthalpy of fusion, and thermodynamic properties of urea, Zhur. Prikl. Khim. (Leningrad), 1986, 59, 1456-1459. [all data]

Parks, Huffman, et al., 1933
Parks, G.S.; Huffman, H.M.; Barmore, M., Thermal data on organic compounds. XI. The heat capacities, entropies and free energies of ten compounds containing oxygen or nitrogen. J. Am. Chem. Soc., 1933, 55, 2733-2740. [all data]

Gibson, Latimer, et al., 1920
Gibson, G.E.; Latimer, W.M.; Parks, G.S., Entropy changes at low temperatures. I. Formic acid and urea. A test of the third law of thermodynamics, J. Am. Chem. Soc., 1920, 42, 1533-1542. [all data]

Gambino and Bros, 1988
Gambino, M.; Bros, J.P., Capacite calorifique de l'uree et de quelques melanges eutectiques a base d'uree entre 30 et 140°C, Thermochim. Acta, 1988, 127, 223-236. [all data]

Sasaki and Yokotake, 1966
Sasaki, K.; Yokotake, T., Thermodynamic properties of the products in SO₃-NH₃ reaction. II. Specific heats of sulfamide and ammonium sulfamate, Tokyo Kogyo Shikenshi Hokohu, 1966, 61, 309-314. [all data]

Ruehrwein and Huffman, 1946
Ruehrwein, R.A.; Huffman, H.M., Thermal data. XIX. The heat capacity, entropy and free energy of urea, J. Am. Chem. Soc., 1946, 68, 1759-1761. [all data]

Campbell and Campbell, 1940
Campbell, A.N.; Campbell, A.J.R., The heats of solution, heats of formation, specific heats and equilibrium diagrams of certain molecular compounds. J. Am. Chem. Soc., 1940, 62, 291-297. [all data]

Notes

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Symbols used in this document:

C_p,solid	Constant pressure heat capacity of solid
S°_{solid,1 bar}	Entropy of solid at standard conditions (1 bar)
Δ_cH°_solid	Enthalpy of combustion of solid at standard conditions
Δ_fH°_solid	Enthalpy of formation of solid at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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