Methane

Formula: CH₄
Molecular weight: 16.0425
IUPAC Standard InChI: InChI=1S/CH4/h1H4
IUPAC Standard InChIKey: VNWKTOKETHGBQD-UHFFFAOYSA-N
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
The 3d structure may be viewed using Java or Javascript.
Other names: Marsh gas; Methyl hydride; CH4; Fire Damp; R 50; Biogas; R 50 (refrigerant)
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Information on this page:
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
- Mass spectrum (electron ionization)
- Fluid Properties
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Gas phase thermochemistry data

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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
Δ_fH°_gas	-17.89	kcal/mol	Review	Chase, 1998	Data last reviewed in March, 1961
Δ_fH°_gas	-17.8 ± 0.07	kcal/mol	Review	Manion, 2002	adopted recommendation of Gurvich, Veyts, et al., 1991; DRB
Δ_fH°_gas	-17.8 ± 0.1	kcal/mol	Ccb	Pittam and Pilcher, 1972	ALS
Δ_fH°_gas	-17.889 ± 0.075	kcal/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; ALS
Δ_fH°_gas	-17.54 ± 0.26	kcal/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -17.97 kcal/mol; ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_gas	-212.88 ± 0.09	kcal/mol	Ccb	Pittam and Pilcher, 1972	Corresponding Δ_fHº_gas = -17.80 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-212.798 ± 0.072	kcal/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; Corresponding Δ_fHº_gas = -17.883 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-213.14 ± 0.26	kcal/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -212.07 ± 0.25 kcal/mol; Corresponding Δ_fHº_gas = -17.54 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-212.753 ± 0.072	kcal/mol	Cm	Rossini, 1931	Corresponding Δ_fHº_gas = -17.928 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_gas	45.09 ± 0.10	cal/mol*K	N/A	Colwell J.H., 1963	The calorimetric value is significantly higher than the statistically calculated entropy, 186.26 J/molK, 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/molK 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}	44.515	cal/mol*K	Review	Chase, 1998	Data last reviewed in March, 1961

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
8.346 ± 0.060	279.	Halford J.O., 1957	GT

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
7.954	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
8.009	200.
8.530	298.15
8.547	300.
9.711	400.
11.14	500.
12.61	600.
14.01	700.
15.32	800.
16.52	900.
17.63	1000.
18.62	1100.
19.52	1200.
20.33	1300.
21.06	1400.
21.72	1500.
22.31	1600.
22.84	1700.
23.33	1800.
23.78	1900.
24.197	2000.
24.577	2100.
24.931	2200.
25.263	2300.
25.574	2400.
25.868	2500.
26.145	2600.
26.410	2700.
26.663	2800.
26.905	2900.
27.139	3000.

Gas Phase Heat Capacity (Shomate Equation)

C_p° = 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
C_p = heat capacity (cal/mol*K)
H° = standard enthalpy (kcal/mol)
S° = standard entropy (cal/mol*K)
t = temperature (K) / 1000.

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Temperature (K)	298. to 1300.	1300. to 6000.
A	-0.168028	20.50960
B	25.92670	2.692321
C	-10.16290	-0.505293
D	1.401240	0.033028
E	0.162181	-6.315060
F	-18.36610	-36.69520
G	37.93411	53.63631
H	-17.89510	-17.89510
Reference	Chase, 1998	Chase, 1998
Comment	Data last reviewed in March, 1961	Data last reviewed in March, 1961

IR Spectrum

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Data compiled by: Coblentz Society, Inc.

GAS (150 mmHg DILUTED TO A TOTAL PRESSURE OF 600 mmHg WITH N2); DOW KBr FOREPRISM; DIGITIZED BY NIST FROM HARD COPY (FROM TWO SEGMENTS); 4 cm^-1 resolution

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Vibrational and/or electronic energy levels

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Data compiled by: Takehiko Shimanouchi

Symmetry: T_d Symmetry Number σ = 12

Sym.	No	Approximate	Selected Freq.		Infrared		Raman		Comments

Species		type of mode	Value	Rating	Value	Phase	Value	Phase

a₁	1	Sym str	2917	A	ia		2917.0	gas
e	2	Deg deform	1534	A	1533 ia	gas	1533.6		Observed through Coriolis interaction with ν₄
f₂	3	Deg str	3019	A	3018.9	gas	3019.5
f₂	4	Deg deform	1306	C	1306.2	gas

Source: Shimanouchi, 1972

Notes

Inactive

0~1 cm^-1 uncertainty

3~6 cm^-1 uncertainty

References

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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]

Shimanouchi, 1972
Shimanouchi, T., Tables of Molecular Vibrational Frequencies Consolidated Volume I, National Bureau of Standards, 1972, 1-160. [all data]

Notes

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Symbols used in this document:

C_p,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)
Δ_cH°_gas	Enthalpy of combustion of gas at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions

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

Data at NIST subscription sites:

Gas phase thermochemistry data

Constant pressure heat capacity of gas

Constant pressure heat capacity of gas

Gas Phase Heat Capacity (Shomate Equation)

IR Spectrum

Vibrational and/or electronic energy levels

Symmetry: Td Symmetry Number σ = 12

Notes

References

Notes

Symmetry: T_d Symmetry Number σ = 12