Methane - The NIST WebBook

Methane

• Formula: CH4
• Molecular weight: 16.0425
• IUPAC Standard InChI: InChI=1S/CH4/h1H4 Copy
• IUPAC Standard InChIKey: VNWKTOKETHGBQD-UHFFFAOYSA-N Copy
• CAS Registry Number: 74-82-8
• Chemical structure: This structure is also available as a 2d Mol file or as a computed 3d SD file View 3d structure (requires JavaScript / HTML 5)
• Other names: Marsh gas; Methyl hydride; CH4; Fire Damp; R 50; Biogas; R 50 (refrigerant)
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• Information on this page:
  • Gas phase thermochemistry data
  • References
  • Notes
• Other data available:
  • Phase change data
  • Reaction thermochemistry data: reactions 1 to 50, reactions 51 to 100, reactions 101 to 112
  • Henry's Law data
  • Gas phase ion energetics data
  • Ion clustering data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • Vibrational and/or electronic energy levels
  • Fluid Properties
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Gas phase thermochemistry data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments: DRB - Donald R. Burgess, Jr. ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow

Quantity	Value	Units	Method	Reference	Comment
ΔfH°gas	-74.87	kJ/mol	Review	Chase, 1998	Data last reviewed in March, 1961
ΔfH°gas	-74.6 ± 0.3	kJ/mol	Review	Manion, 2002	adopted recommendation of Gurvich, Veyts, et al., 1991; DRB
ΔfH°gas	-74.5 ± 0.4	kJ/mol	Ccb	Pittam and Pilcher, 1972	ALS
ΔfH°gas	-74.85 ± 0.31	kJ/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; ALS
ΔfH°gas	-73.4 ± 1.1	kJ/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -75.19 kJ/mol; ALS
Quantity	Value	Units	Method	Reference	Comment
ΔcH°gas	-890.7 ± 0.4	kJ/mol	Ccb	Pittam and Pilcher, 1972	Corresponding ΔfHºgas = -74.48 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
ΔcH°gas	-890.35 ± 0.30	kJ/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; Corresponding ΔfHºgas = -74.822 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
ΔcH°gas	-891.8 ± 1.1	kJ/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -887.3 ± 1.0 kJ/mol; Corresponding ΔfHºgas = -73.39 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
ΔcH°gas	-890.16 ± 0.30	kJ/mol	Cm	Rossini, 1931	Corresponding ΔfHºgas = -75.010 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°gas	188.66 ± 0.42	J/mol*K	N/A	Colwell J.H., 1963	The calorimetric value is significantly higher than the statistically calculated entropy, 186.26 J/mol*K, which remains the best value for use in thermodynamic calculations [ Vogt G.J., 1976, Friend D.G., 1989, Gurvich, Veyts, et al., 1989]. Earlier the value of 185.3 J/mol*K was calculated from experimental data [ Giauque W.F., 1931]. The value of S(298.15 K)=185.94 J/mol*K was obtained by high accuracy ab initio calculation [ East A.L.L., 1997].; GT
Quantity	Value	Units	Method	Reference	Comment
S°gas,1 bar	186.25	J/mol*K	Review	Chase, 1998	Data last reviewed in March, 1961

Constant pressure heat capacity of gas

Cp,gas (J/mol*K)	Temperature (K)	Reference	Comment
34.92 ± 0.25	279.	Halford J.O., 1957	GT

Constant pressure heat capacity of gas

Cp,gas (J/mol*K)	Temperature (K)	Reference	Comment
33.28	100.	Gurvich, Veyts, et al., 1989	p=1 bar. Because of more precise method of calculation, the recommended values are more accurate, especially at high temperatures, than those obtained by [ McDowell R.S., 1963] and often regarded as reference data [ Friend D.G., 1989].; GT
33.51	200.
35.69	298.15
35.76	300.
40.63	400.
46.63	500.
52.74	600.
58.60	700.
64.08	800.
69.14	900.
73.75	1000.
77.92	1100.
81.68	1200.
85.07	1300.
88.11	1400.
90.86	1500.
93.33	1600.
95.58	1700.
97.63	1800.
99.51	1900.
101.24	2000.
102.83	2100.
104.31	2200.
105.70	2300.
107.00	2400.
108.23	2500.
109.39	2600.
110.50	2700.
111.56	2800.
112.57	2900.
113.55	3000.

Gas Phase Heat Capacity (Shomate Equation)

Cp° = A + B*t + C*t2 + D*t3 + E/t2 H° − H°298.15= A*t + B*t2/2 + C*t3/3 + D*t4/4 − E/t + F − H S° = A*ln(t) + B*t + C*t2/2 + D*t3/3 − E/(2*t2) + G Cp = heat capacity (J/mol*K) H° = standard enthalpy (kJ/mol) S° = standard entropy (J/mol*K) t = temperature (K) / 1000.

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View table.

Temperature (K)	298. to 1300.	1300. to 6000.
A	-0.703029	85.81217
B	108.4773	11.26467
C	-42.52157	-2.114146
D	5.862788	0.138190
E	0.678565	-26.42221
F	-76.84376	-153.5327
G	158.7163	224.4143
H	-74.87310	-74.87310
Reference	Chase, 1998	Chase, 1998
Comment	Data last reviewed in March, 1961	Data last reviewed in March, 1961

References

Go To: Top, Gas phase thermochemistry data, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Chase, 1998 Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Manion, 2002 Manion, J.A., Evaluated Enthalpies of Formation of the Stable Closed Shell C1 and C2 Chlorinated Hydrocarbons, J. Phys. Chem. Ref. Data, 2002, 31, 1, 123-172, https://doi.org/10.1063/1.1420703 . [all data]

Gurvich, Veyts, et al., 1991 Thermodynamic Properties of Individual Substances, 4th edition, Volume 2, Gurvich, L.V.; Veyts, I.V.; Alcock, C.B.;, ed(s)., Hemisphere, New York, 1991. [all data]

Pittam and Pilcher, 1972 Pittam, D.A.; Pilcher, G., Measurements of heats of combustion by flame calorimetry. Part 8.-Methane, ethane, propane, n-butane and 2-methylpropane, J. Chem. Soc. Faraday Trans. 1, 1972, 68, 2224-2229. [all data]

Prosen and Rossini, 1945 Prosen, E.J.; Rossini, F.D., Heats of combustion and formation of the paraffin hydrocarbons at 25° C, J. Res. NBS, 1945, 263-267. [all data]

Roth and Banse, 1932 Roth, W.A.; Banse, H., Die verbrennungs- und bildungswarme von kohlenoxyd und methan, Arch. Eisenhutten., 1932, 6, 43-46. [all data]

Cox and Pilcher, 1970 Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Rossini, 1931 Rossini, F.D., The heats of combustion of methane and carbon monoxide, J. Res. NBS, 1931, 6, 37-49. [all data]

Colwell J.H., 1963 Colwell J.H., Thermodynamic properties of CH4 and CD4. Interpretation of the properties of solid, J. Chem. Phys., 1963, 39, 635-653. [all data]

Vogt G.J., 1976 Vogt G.J., Entropy and heat capacity of methane; spin-species conversion, J. Chem. Thermodyn., 1976, 8, 1011-1031. [all data]

Friend D.G., 1989 Friend D.G., Thermophysical properties of methane, J. Phys. Chem. Ref. Data, 1989, 18, 583-638. [all data]

Gurvich, Veyts, et al., 1989 Gurvich, L.V.; Veyts, I.V.; Alcock, C.B., Thermodynamic Properties of Individual Substances, 4th ed.; Vols. 1 and 2, Hemisphere, New York, 1989. [all data]

Giauque W.F., 1931 Giauque W.F., The entropies of methane and ammonia, Phys. Rev., 1931, 38, 196-197. [all data]

East A.L.L., 1997 East A.L.L., Ab initio statistical thermodynamical models for the computation of third-law entropies, J. Chem. Phys., 1997, 106, 6655-6674. [all data]

Halford J.O., 1957 Halford J.O., Standard heat capacities of gaseous methanol, ethanol, methane and ethane at 279 K by thermal conductivity, J. Phys. Chem., 1957, 61, 1536-1539. [all data]

McDowell R.S., 1963 McDowell R.S., Thermodynamic functions of methane, J. Chem. Eng. Data, 1963, 8, 547-548. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, References

• Symbols used in this document:

  Cp,gas	Constant pressure heat capacity of gas
  S°gas	Entropy of gas at standard conditions
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  ΔcH°gas	Enthalpy of combustion of gas at standard conditions
  ΔfH°gas	Enthalpy of formation of gas at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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