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
  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)
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Phase change data
  • Henry's Law data
  • Gas phase ion energetics data
  • References
  • Notes
• Other data available:
  • Reaction thermochemistry data: reactions 1 to 50, reactions 51 to 100, reactions 101 to 112
  • Ion clustering data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • Vibrational and/or electronic energy levels
  • Fluid Properties
• Data at other public NIST sites:
  • Microwave spectra (on physics lab web site)
  • Electron-Impact Ionization Cross Sections (on physics web site)
  • Gas Phase Kinetics Database
• Options:
  • Switch to SI units

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• NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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Gas phase thermochemistry data

Go To: Top, Phase change data, Henry's Law data, Gas phase ion energetics data, References, Notes

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

Constant pressure heat capacity of gas

Constant pressure heat capacity of gas

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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View table.

Phase change 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:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
DH - Eugene S. Domalski and Elizabeth D. Hearing
AC - William E. Acree, Jr., James S. Chickos

Enthalpy of vaporization

Enthalpy of vaporization

Δ_vapH = A exp(-αT_r) (1 − T_r)^β
    Δ_vapH = Enthalpy of vaporization (at saturation pressure) (kcal/mol)
    T_r = reduced temperature (T / T_c)

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Entropy of vaporization

Antoine Equation Parameters

log₁₀(P) = A − (B / (T + C))
    P = vapor pressure (atm)
    T = temperature (K)

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Enthalpy of sublimation

Enthalpy of phase transition

Entropy of phase transition

Henry's Law 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 by: Rolf Sander

Henry's Law constant (water solution)

k_H(T) = k°_H exp(d(ln(k_H))/d(1/T) ((1/T) - 1/(298.15 K)))
k°_H = Henry's law constant for solubility in water at 298.15 K (mol/(kg*bar))
d(ln(k_H))/d(1/T) = Temperature dependence constant (K)

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, References, Notes

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

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to CH₄⁺ (ion structure unspecified)

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

CH₃^- +  =

By formula: CH₃^- + H⁺ = CH₄

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics 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]

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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]

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

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

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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]

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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
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Streng, 1971
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Ambrose and Tsonopoulos, 1995
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Younglove and Ely, 1987
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Terry, Lynch, et al., 1969
Terry, M.J.; Lynch, J.T.; Bunclark, M.; Mansell, K.R.; Staveley, L.A.K., The Densities of Liquid Argon, Krypton, Xenon, Oxygen, Nitrogen, Carbon Monoxide, Methane and Carbon Tetrafluoride Along the Orthobaric Liquid Curve, J. Chem. Thermodyn., 1969, 1, 413. [all data]

Vogt and Pitzer, 1976
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Frank and Clusius, 1937
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Stock, Henning, et al., 2006
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Boublik, Fried, et al., 1984
Boublik, T.; Fried, V.; Hala, E., The Vapour Pressures of Pure Substances: Selected Values of the Temperature Dependence of the Vapour Pressures of Some Pure Substances in the Normal and Low Pressure Region, 2nd ed., Elsevier, New York, 1984, 972. [all data]

Stephenson and Malanowski, 1987
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Majer and Svoboda, 1985
Majer, V.; Svoboda, V., Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation, Blackwell Scientific Publications, Oxford, 1985, 300. [all data]

Ott, Goates, et al., 1972
Ott, J. Bevan; Goates, J. Rex; Lamb, John D., Solid-liquid phase equilibria in water + ethylene glycol, The Journal of Chemical Thermodynamics, 1972, 4, 1, 123-126, https://doi.org/10.1016/S0021-9614(72)80015-6 . [all data]

Reid, 1972
Reid, Robert C., Handbook on vapor pressure and heats of vaporization of hydrocarbons and related compounds, R. C. Wilhort and B. J. Zwolinski, Texas A Research Foundation. College Station, Texas(1971). 329 pages.$10.00, AIChE J., 1972, 18, 6, 1278-1278, https://doi.org/10.1002/aic.690180637 . [all data]

Ambrose, Counsell, et al., 1970
Ambrose, D.; Counsell, J.F.; Davenport, A.J., The use of Chebyshev polynomials for the representation of vapour pressures between the triple point and the critical point, The Journal of Chemical Thermodynamics, 1970, 2, 2, 283-294, https://doi.org/10.1016/0021-9614(70)90093-5 . [all data]

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Hestermans, P.; White, David, THE VAPOR PRESSURE, HEAT OF VAPORIZATION AND HEAT CAPACITY OF METHANE FROM THE BOILING POINT TO THE CRITICAL TEMPERATURE, J. Phys. Chem., 1961, 65, 2, 362-365, https://doi.org/10.1021/j100820a044 . [all data]

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Prydz and Goodwin, 1972
Prydz, R.; Goodwin, R.D., Experimental Melting and Vapor Pressures of Methane, J. Chem. Thermodyn., 1972, 4, 1, 127-133, https://doi.org/10.1016/S0021-9614(72)80016-8 . [all data]

Regnier, 1972
Regnier, J., Tension de Vapeur de L'Ethane Entre 80 et 135 K, J. Chim. Phys., 1972, 69, 942-944. [all data]

Cutler and Morrison, 1965
Cutler, A.J.B.; Morrison, J.A., Excess Thermodynamic Functions for Liquid Mixtures of Methane+Propane, Trans. Faraday Soc., 1965, 61, 429-442, https://doi.org/10.1039/tf9656100429 . [all data]

Bondi, 1963
Bondi, A., Heat of Siblimation of Molecular Crystals: A Catalog of Molecular Structure Increments., J. Chem. Eng. Data, 1963, 8, 3, 371-381, https://doi.org/10.1021/je60018a027 . [all data]

Armstrong, Brickwedde, et al., 1955
Armstrong, George T.; Brickwedde, F.G.; Scott, R.B., Vapor pressures of the methanes, J. RES. NATL. BUR. STAN., 1955, 55, 1, 39, https://doi.org/10.6028/jres.055.005 . [all data]

Jones, 1960
Jones, A.H., Sublimation Pressure Data for Organic Compounds., J. Chem. Eng. Data, 1960, 5, 2, 196-200, https://doi.org/10.1021/je60006a019 . [all data]

Tickner and Lossing, 1951
Tickner, A.W.; Lossing, F.P., The Measurement of Low Vapor Pressures by Means of a Mass Spectrometer., J. Phys. Chem., 1951, 55, 5, 733-740, https://doi.org/10.1021/j150488a013 . [all data]

Stull, 1947
Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Berkowitz, Greene, et al., 1987
Berkowitz, J.; Greene, J.P.; Cho, H.; Ruscic, B., The ionization potentials of CH₄ and CD₄, J. Chem. Phys., 1987, 86, 674. [all data]

Chatham, Hils, et al., 1984
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Plessis, Marmet, et al., 1983
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Selim and El-Kholy, 1975
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Debies and Rabalais, 1975
Debies, T.P.; Rabalais, J.W., Calculated photoionization cross-sections and angular distributions for the isoelectronic series Ne, HF, H₂O, NH₃, and CH₄, J. Am. Chem. Soc., 1975, 97, 487. [all data]

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Rabalais, J.W.; Debies, T.P.; Berkosky, J.L.; Huang, J.-T.J.; Ellison, F.O., Calculated photoionization cross sections relative experimental photoionization intensities for a selection of small molecules, J. Chem. Phys., 1974, 61, 516. [all data]

Morrison and Traeger, 1973
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Potts and Price, 1972
Potts, A.W.; Price, W.C., The photoelectron spectra of methane, silane germane and stannane, Proc. R. Soc. London A:, 1972, 165. [all data]

Finney and Harrison, 1972
Finney, C.D.; Harrison, A.G., A third-derivative method for determining electron-impact onset potentials, Int. J. Mass Spectrom. Ion Phys., 1972, 9, 221. [all data]

Bergmark, Rabalais, et al., 1972
Bergmark, T.; Rabalais, J.W.; Werme, L.O.; Karlsson, L.; Siegbahn, K., High-resolution electron spectra of methane, thiophene, 2-bromothiphene, and 3-bromothiophene in Electron Spectroscopy, ed. D.A. Shirley (North-Holland Pub. Co., Amsterdam), 1972. [all data]

Rabalais, Bergmark, et al., 1971
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Chupka and Berkowitz, 1971
Chupka, W.A.; Berkowitz, J., Photoionization of methane: ionization potential and proton affinity of CH₄, J. Chem. Phys., 1971, 54, 4256. [all data]

Pullen, Carlson, et al., 1970
Pullen, B.P.; Carlson, T.A.; Moddeman, W.E.; Schweitzer, G.K.; Bull, W.E., Photoelectron spectra of methane, silane, germane, methyl fluoride, difluoromethane, and trifluoromethane, J. Chem. Phys., 1970, 53, 768. [all data]

Brundle, Robin, et al., 1970
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Lossing and Semeluk, 1969
Lossing, F.P.; Semeluk, G.P., Threshold ionization efficiency curves for monoenergetic electron impact on H₂, D₂, CH₄ and CD₄, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 408. [all data]

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Chupka, 1968
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Check, Faust, et al., 2001
Check, C.E.; Faust, T.O.; Bailey, J.M.; Wright, B.J.; Gilbert, T.M.; Sunderlin, L.S., Addition of Polarization and Diffuse Functions to the LANL2DZ Basis Set for P-Block Elements, J. Phys. Chem. A,, 2001, 105, 34, 8111, https://doi.org/10.1021/jp011945l . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, References

• Symbols used in this document:
  

  AE	Appearance energy
  Cp,gas	Constant pressure heat capacity of gas
  IE (evaluated)	Recommended ionization energy
  Pc	Critical pressure
  Ptriple	Triple point pressure
  S°gas	Entropy of gas at standard conditions
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  Tboil	Boiling point
  Tc	Critical temperature
  Tfus	Fusion (melting) point
  Ttriple	Triple point temperature
  Vc	Critical volume
  d(ln(kH))/d(1/T)	Temperature dependence parameter for Henry's Law constant
  k°H	Henry's Law constant at 298.15K
  ΔHtrs	Enthalpy of phase transition
  ΔStrs	Entropy of phase transition
  ΔcH°gas	Enthalpy of combustion of gas at standard conditions
  ΔfH°gas	Enthalpy of formation of gas at standard conditions
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔsubH	Enthalpy of sublimation
  ΔvapH	Enthalpy of vaporization
  ΔvapS	Entropy of vaporization
  ρc	Critical density

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