Acetylene

• Formula: C₂H₂
• Molecular weight: 26.0373
• IUPAC Standard InChI: InChI=1S/C2H2/c1-2/h1-2H Copy

  
• IUPAC Standard InChIKey: HSFWRNGVRCDJHI-UHFFFAOYSA-N Copy
• CAS Registry Number: 74-86-2
• 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: Ethyne; Ethine; Narcylen; C2H2; Acetylen; UN 1001; Vinylene
• 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
  • Ion clustering data
  • Mass spectrum (electron ionization)
  • References
  • Notes
• Other data available:
  • Reaction thermochemistry data
  • IR Spectrum
  • Vibrational and/or electronic energy levels
  • Gas Chromatography
• 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:
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Data at NIST subscription sites:

• NIST / TRC Web Thermo Tables, "lite" edition (thermophysical and thermochemical data)
• 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, Ion clustering data, Mass spectrum (electron ionization), 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

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 (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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Phase change data

Go To: Top, Gas phase thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), 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:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
CAL - James S. Chickos, William E. Acree, Jr., Joel F. Liebman, Students of Chem 202 (Introduction to the Literature of Chemistry), University of Missouri -- St. Louis

Enthalpy of vaporization

Antoine Equation Parameters

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

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Enthalpy of sublimation

Enthalpy of fusion

Entropy of fusion

Henry's Law data

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), References, Notes

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

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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 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
LL - Sharon G. Lias and Joel F. Liebman

View reactions leading to C₂H₂⁺ (ion structure unspecified)

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

C₂H^- +  =

By formula: C₂H^- + H⁺ = C₂H₂

Ion clustering data

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, Mass spectrum (electron ionization), 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:
RCD - Robert C. Dunbar
B - John E. Bartmess
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

 +  = ( • )

By formula: Al⁺ + C₂H₂ = (Al⁺ • C₂H₂)

 +  = C₂H₂Br^-

By formula: Br^- + C₂H₂ = C₂H₂Br^-

COS⁺ +  = (COS⁺ • )

By formula: COS⁺ + C₂H₂ = (COS⁺ • C₂H₂)

C₂H₂⁺ +  = (C₂H₂⁺ • )

By formula: C₂H₂⁺ + C₂H₂ = (C₂H₂⁺ • C₂H₂)

 +  = ( • )

By formula: Co⁺ + C₂H₂ = (Co⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Cr⁺ + C₂H₂ = (Cr⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Cu⁺ + C₂H₂ = (Cu⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Fe⁺ + C₂H₂ = (Fe⁺ • C₂H₂)

 +  = ( • )

By formula: La⁺ + C₂H₂ = (La⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Ni⁺ + C₂H₂ = (Ni⁺ • C₂H₂)

Enthalpy of reaction

Rh⁺ +  = (Rh⁺ • )

By formula: Rh⁺ + C₂H₂ = (Rh⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Sc⁺ + C₂H₂ = (Sc⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Ti⁺ + C₂H₂ = (Ti⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: V⁺ + C₂H₂ = (V⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Y⁺ + C₂H₂ = (Y⁺ • C₂H₂)

Enthalpy of reaction

Mass spectrum (electron ionization)

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, Ion clustering 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 by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Spectrum

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Additional Data

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), Notes

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

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Ambrose, 1956
Ambrose, D., The vapour pressures and critical temperatures of acetylene and carbon dioxide, Trans. Faraday Soc., 1956, 52, 772, https://doi.org/10.1039/tf9565200772 . [all data]

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Ambrose and Townsend, 1964, 2
Ambrose, D.; Townsend, R., Vapour Pressure of Acetylene, Trans. Faraday Soc., 1964, 60, 1025-1029, https://doi.org/10.1039/tf9646001025 . [all data]

Ambrose, 1956, 2
Ambrose, D., The Vapour Pressures and Critical Temperatures of Acetylene and Carbon Dioxide, Trans. Faraday Soc., 1956, 52, 772-781, https://doi.org/10.1039/tf9565200772 . [all data]

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Hunter and Lias, 1998
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Plessis and Marmet, 1986
Plessis, P.; Marmet, P., Electroionization study of acetylene and fragment ions, Int. J. Mass Spectrom. Ion Processes, 1986, 70, 23. [all data]

Hayaishi, Iwata, et al., 1982
Hayaishi, T.; Iwata, S.; Sasanuma, M.; Ishiguro, E.; Morioka, Y.; Iida, Y.; Nakamura, M., Photoionisation mass spectrometric study of acetylene in the VUV region, J. Phys. B:, 1982, 15, 79. [all data]

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Bieri, Schmelzer, et al., 1980
Bieri, G.; Schmelzer, A.; Asbrink, L.; Jonsson, M., Fluorine and the fluoroderivatives of acetylene and diacetylene studied by 30.4 nm He(II) photoelectron spectroscopy, Chem. Phys., 1980, 49, 213. [all data]

Suzuki and Maeda, 1978
Suzuki, I.H.; Maeda, K., Ionization efficiency curves of acetylene by mono-energetic electron impact, Adv. Mass Spectrom., 1978, 7, 182. [all data]

Suzuki and Maeda, 1977
Suzuki, I.H.; Maeda, K., Ionization efficiency curves of acetylene by electron impact, Mass Spectrosc. (Tokyo), 1977, 25, 223. [all data]

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Dibeler and Walker, 1973
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Lossing, 1970
Lossing, F.P., Threshold ionization of acetylene by monoenergetic electron impact, Intern. J. Mass Spectrom. Ion Phys., 1970, 5, 190. [all data]

Omura, Kaneko, et al., 1969
Omura, I.; Kaneko, T.; Yamada, Y.; Tanaka, K., Mass spectrometric studies of photoionization. IV. Acetylene and propyne, J. Phys. Soc. Japan, 1969, 27, 178. [all data]

Williams and Hamill, 1968
Williams, J.M.; Hamill, W.H., Ionization potentials of molecules and free radicals and appearance potentials by electron impact in the mass spectrometer, J. Chem. Phys., 1968, 49, 4467. [all data]

Collins, Winters, et al., 1968
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Baker and Turner, 1968
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Brehm, 1966
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Cavell, R.G.; Allison, D.A., Photoelectron spectra of acetylene with He(I), He(II) , Zr M175»_{zeta}, MgK»α radiation sources, J. Chem. Phys., 1978, 69, 159. [all data]

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Davister and Locht, 1994
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Shiromaru, Achiba, et al., 1987
Shiromaru, H.; Achiba, Y.; Kimura, K.; Lee, Y.T., Determination of the C-H bond dissociation energies of ethylene and acetylene by observation of the threshold energies of H⁺ formation by synchrotron radiation, J. Phys. Chem., 1987, 91, 17. [all data]

Stockigt, Schwarz, et al., 1996
Stockigt, D.; Schwarz, J.; Schwarz, H., Theoretical and Experimental Studies on the Bond Dissociation Energies of Al(methane)+, Al(acetylene)+, Al(ethene)+, and Al(ethane)+, J. Phys. Chem., 1996, 100, 21, 8786, https://doi.org/10.1021/jp960060k . [all data]

Wild, Milley, et al., 2000
Wild, D.A.; Milley, P.J.; Loh, Z.M.; Wolynec, P.P.; Weiser, P.S.; Bieske, E.J., Structural and Energetic Properties of the Br--C2H2 Anion Complex from Rotationally Resolved Mid-infrared Spectra And ab initio Calculations, J. Chem. Phys., 2000, 113, 3, 1075, https://doi.org/10.1063/1.481919 . [all data]

Graul S.T. and Bowers, 1991
Graul S.T.; Bowers, M.T., Dynamics of Metastable Dissociation and Photodissociation of the Gas Phase Cluster Ion (OCS.C2H2)+, J. Phys. Chem., 1991, 95, 21, 8328, https://doi.org/10.1021/j100174a055 . [all data]

Orlando, Friedman, et al., 1990
Orlando, T.M.; Friedman, A.; Maier, J.P., Photodissociation Spectroscopy of the [OCS C2H2]+ Cluster, J. Chem. Phys., 1990, 92, 12, 7365, https://doi.org/10.1063/1.458222 . [all data]

Ono and Ng, 1982
Ono, Y.; Ng, C.Y., A Study of the Unimolecular Decomposition of the (C2H2)2+ Complex, J. Chem. Phys., 1982, 77, 6, 2947, https://doi.org/10.1063/1.444216 . [all data]

Surya, Ranatunga, et al., 1997
Surya, P.I.; Ranatunga, D.R.A.; Freiser, B.S., Infrared Multiphoton Dissociation of MC4H6+ [M=Fe, Co or Ni: C4H6=1,3-butadiene or (C2H2)(C2H4), J. Am. Chem. Soc., 1997, 119, 14, 3351, https://doi.org/10.1021/ja963200c . [all data]

Armentrout and Kickel, 1994
Armentrout, P.B.; Kickel, B.L., Gas Phase Thermochemistry of Transition Metal Ligand Systems: Reassessment of Values and Periodic Trends, in Organometallic Ion Chemistry, B. S. Freiser, ed, 1994. [all data]

Chen and Armetrout, 1995
Chen, Y.M.; Armetrout, P.B., Activation of C2H6, C3H8, and c-C3H6 by Gas-Phase Rh+ and the Thermochemistry of Rh-Ligand Complexes, J. Am. Chem. Soc., 1995, 117, 36, 9291, https://doi.org/10.1021/ja00141a022 . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), 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,1 bar	Entropy of gas at standard conditions (1 bar)
  T	Temperature
  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
  ΔfH°gas	Enthalpy of formation of gas at standard conditions
  ΔfusH	Enthalpy of fusion
  ΔfusS	Entropy of fusion
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔsubH	Enthalpy of sublimation
  ΔvapH	Enthalpy of vaporization
  ρc	Critical density

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