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
  • Reaction thermochemistry data
  • References
  • Notes
• Other data available:
  • Phase change data
  • Henry's Law data
  • Gas phase ion energetics data
  • Ion clustering data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • 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:
  • Switch to SI units

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Gas phase thermochemistry data

Go To: Top, Reaction thermochemistry 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

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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Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry 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:
B - John E. Bartmess
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
RCD - Robert C. Dunbar
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
MS - José A. Martinho Simões

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

C₂H^- +  =

By formula: C₂H^- + H⁺ = C₂H₂

COS⁺ +  = (COS⁺ • )

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

 +  = ( • )

By formula: Co⁺ + C₂H₂ = (Co⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Ni⁺ + C₂H₂ = (Ni⁺ • C₂H₂)

Enthalpy of reaction

2 +  =

By formula: 2H₂ + C₂H₂ = C₂H₆

=  + 

By formula: C₇H₈ = C₅H₆ + C₂H₂

C₂Na₂ (cr) + 2 (l) = 2( • 1418) (solution) +  (g)

By formula: C₂Na₂ (cr) + 2H₂O (l) = 2(HNaO • 1418H₂O) (solution) + C₂H₂ (g)

C₂HCs (cr) +  (l) = ( • 1031) (solution) +  (g)

By formula: C₂HCs (cr) + H₂O (l) = (HCsO • 1031H₂O) (solution) + C₂H₂ (g)

C₂HNa (cr) +  (l) = ( • 1418) (solution) +  (g)

By formula: C₂HNa (cr) + H₂O (l) = (HNaO • 1418H₂O) (solution) + C₂H₂ (g)

 +  = ( • )

By formula: Cu⁺ + C₂H₂ = (Cu⁺ • C₂H₂)

Enthalpy of reaction

2 =

By formula: 2C₂H₂ = C₄H₄

Rh⁺ +  = (Rh⁺ • )

By formula: Rh⁺ + C₂H₂ = (Rh⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Cr⁺ + C₂H₂ = (Cr⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Ti⁺ + C₂H₂ = (Ti⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: La⁺ + C₂H₂ = (La⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Sc⁺ + C₂H₂ = (Sc⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: V⁺ + C₂H₂ = (V⁺ • C₂H₂)

Enthalpy of reaction

 +  = ( • )

By formula: Y⁺ + C₂H₂ = (Y⁺ • C₂H₂)

Enthalpy of reaction

 +  = C₂H₂Br^-

By formula: Br^- + C₂H₂ = C₂H₂Br^-

C₂Ag₂ (cr) + 2( • 12.3) (solution) =  (aq) + 2 (cr)

By formula: C₂Ag₂ (cr) + 2(HCl • 12.3H₂O) (solution) = C₂H₂ (aq) + 2AgCl (cr)

(CAS Reg. No. 25012-81-1 • 4294967295) +  = CAS Reg. No. 25012-81-1

By formula: (CAS Reg. No. 25012-81-1 • 4294967295C₂H₂) + C₂H₂ = CAS Reg. No. 25012-81-1

 +  = ( • )

By formula: Al⁺ + C₂H₂ = (Al⁺ • C₂H₂)

=  + 

By formula: C₂H₂Cl₂ = C₂H₂ + Cl₂

=  + 

By formula: C₂H₃Cl = C₂H₂ + HCl

 +  =

By formula: C₅H₆ + C₂H₂ = C₇H₈

C₂H₂⁺ +  = (C₂H₂⁺ • )

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

 +  = ( • )

By formula: Fe⁺ + C₂H₂ = (Fe⁺ • C₂H₂)

=  + 

By formula: C₂H₂I₂ = C₂H₂ + I₂

C₂H₂I₂ =  + 

By formula: C₂H₂I₂ = C₂H₂ + I₂

References

Go To: Top, Gas phase thermochemistry data, Reaction 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]

Wagman, Kilpatrick, et al., 1945
Wagman, D.D.; Kilpatrick, J.E.; Pitzer, K.S.; Rossini, F.D., Heats, equilibrium constants, and free energies of formation of the acetylene hydrocarbons through the pentynes, to 1,500° K, J. Res. NBS, 1945, 35, 467-496. [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]

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]

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]

Conn, Kistiakowsky, et al., 1939
Conn, J.B.; Kistiakowsky, G.B.; Smith, E.A., Heats of organic reactions. VIII. Some further hydrogenations, including those of some acetylenes, J. Am. Chem. Soc., 1939, 61, 1868-1876. [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]

Walsh and Wells, 1975
Walsh, R.; Wells, J.M., The enthalpy of formation of bicyclo[2,2,1]hepta-2,5-diene. Thermodynamic functions of bicyclo[2,2,1]heptane and bicyclo[2,2,1]hepta-2,5-diene, J. Chem. Thermodyn., 1975, 7, 149-154. [all data]

Pedley, Naylor, et al., 1986
Pedley, J.B.; Naylor, R.D.; Kirby, S.P., Thermochemical Data of Organic Compounds, Chapman and Hall, New York, 1986, 1-792. [all data]

Johnson, van Deventer, et al., 1973
Johnson, G.K.; van Deventer, E.H.; Ackerman, J.P.; Hubbard, W.N.; Osborne, D.W.; Flotow, H.L., J. Chem. Thermodyn., 1973, 5, 57. [all data]

Pedley and Rylance, 1977
Pedley, J.B.; Rylance, J., Computer Analysed Thermochemical Data: Organic and Organometallic Compounds, University of Sussex, Brigton, 1977. [all data]

Ader and Hubbard, 1973
Ader, M.; Hubbard, W.N., J. Chem. Thermodyn., 1973, 5, 607. [all data]

Reppe, Schlichting, et al., 1948
Reppe, W.; Schlichting, O.; Klager, K.; Toepel, T., Cyclisierende Polymerisation von Acetylen I Uber Cyclooctatetraen, Justus Liebigs Ann. Chem., 1948, 1-93. [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]

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]

Finch, Gardner, et al., 1991
Finch, A.; Gardner, P.J.; Head, A.J.; Majdi, H.S., Thermochim. Acta, 1991, 180, 325. [all data]

Ervin, Gronert, et al., 1990
Ervin, K.M.; Gronert, S.; Barlow, S.E.; Gilles, M.K.; Harrison, A.G.; Bierbaum, V.M.; DePuy, C.H.; Lin, W.C., Bonds Strengths of Ethylene and Acetylene, J. Am. Chem. Soc., 1990, 112, 15, 5750, https://doi.org/10.1021/ja00171a013 . [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]

Laursen and Pimentel, 1989
Laursen, S.L.; Pimentel, G.C., Matrix-induced intersystem crossing in the photochemistry of the 1,2-dichloroethenes, J. Phys. Chem., 1989, 93, 2328-2333. [all data]

Lacher, Gottlieb, et al., 1962
Lacher, J.R.; Gottlieb, H.B.; Park, J.D., Reaction heats of organic compounds. Part 2.-Heat of addition of hydrogen chloride to acetylene, Trans. Faraday Soc., 1962, 58, 2348-2351. [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]

Furuyama, Golden, et al., 1968
Furuyama, S.; Golden, D.M.; Benson, S.W., The thermochemistry of the gas-phase equilibria trans-1,2-diiodoethylene = acetylene + I₂ and trans-1,2-diiodoethylene = cis-1,2-diiodoethylene, J. Phys. Chem., 1968, 72, 3204-3208. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, References

• Symbols used in this document:
  

  Cp,gas	Constant pressure heat capacity of gas
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  T	Temperature
  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

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