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
  • Reaction thermochemistry data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • Vibrational and/or electronic energy levels
  • References
  • Notes
• Other data available:
  • Henry's Law data
  • Gas phase ion energetics data
  • Ion clustering data
  • Gas Chromatography
• Data at other public NIST sites:
  • Microwave spectra (on physics lab web site)
  • Electron-Impact Ionization Cross Sections (on physics web site)
  • Computational Chemistry Comparison and Benchmark Database
  • Gas Phase Kinetics Database
• Options:
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Data at NIST subscription sites:

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

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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

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

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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:
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

Reaction 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:
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

IR Spectrum

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Data compiled by: Coblentz Society, Inc.

• GAS (50 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

• gas

Mass spectrum (electron ionization)

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

Spectrum

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Additional Data

Vibrational and/or electronic energy levels

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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: Takehiko Shimanouchi

Symmetry:   D_∞h     Symmetry Number σ = 2

Source: Shimanouchi, 1972

Notes

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Mass spectrum (electron ionization), Vibrational and/or electronic energy levels, 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]

Buckingham and Donaghy, 1982
Buckingham, J.; Donaghy, S.M., Dictionary of Organic Compounds: Fifth Edition, Chapman and Hall, New York, 1982, 1. [all data]

Maass and Wright, 1921
Maass, O.; Wright, C.H., SOME PHYSICAL PROPERTIES OF HYDROCARBONS CONTAINING TWO AND THREE CARBON ATOMS., J. Am. Chem. Soc., 1921, 43, 5, 1098-1111, https://doi.org/10.1021/ja01438a013 . [all data]

Morehouse and Maass, 1931
Morehouse, F.R.; Maass, O., The Preparationa and Physical Properties of Ethyl and Methyl Acetylene, Can. J. Res., 1931, 5, 306. [all data]

Maass and Russell, 1918
Maass, O.; Russell, J., Unsaturation and molecular compound formation, J. Am. Chem. Soc., 1918, 40, 1561-1573. [all data]

McIntosh, 1907
McIntosh, D., The physical properties of liquid and solid acetylene., J. Phys. Chem., 1907, 11, 306-17. [all data]

Clark and Din, 1950
Clark, A.M.; Din, F., Equilibria Between Solid, Liquid, and Gaseous Phases at Low Temperature binary systems acetylene - carbon dioxide, acetylene - ethylene and acetylene - ethane, Trans. Faraday Soc., 1950, 46, 901. [all data]

Tsonopoulos and Ambrose, 1996
Tsonopoulos, C.; Ambrose, D., Vapor-Liquid Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic Hydrocarbons, J. Chem. Eng. Data, 1996, 41, 645-656. [all data]

Goloborod'ko and Khodeeva, 1972
Goloborod'ko, N.P.; Khodeeva, S.M., Russ. J. Phys. Chem. (Engl. Transl.), 1972, 46, 235-7. [all data]

Khodeeva, 1966
Khodeeva, S.M., Visual Observation of Gas-Gas Mixture, Russ. J. Phys. Chem. (Engl. Transl.), 1966, 40, 1061-3. [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [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 and Townsend, 1964
Ambrose, D.; Townsend, R., Vapour pressure of acetylene, Trans. Faraday Soc., 1964, 60, 1025, https://doi.org/10.1039/tf9646001025 . [all data]

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]

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]

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]

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]

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]

Burbo, 1943
Burbo, P.Z., Russ. J. Phys. Chem., 1943, 7, 286. [all data]

Miskiewicz, Rieser, et al., 2010
Miskiewicz, Stefan; Rieser, Klaus; Dorfmüller, Thomas, Thermodynamische Untersuchungen an kondensierten Phasen, Berichte der Bunsengesellschaft für physikalische Chemie, 2010, 80, 5, 395-405, https://doi.org/10.1002/bbpc.19760800504 . [all data]

Miskiewicz, Rieser, et al., 1976
Miskiewicz, S.; Rieser, K.; Dorfmuller, T., Thermodynamische Untersuchungen an kondensierten Phasen, Ber. Bunsen-Ges. Physik. Chem., 1976, 80, 5, 395, https://doi.org/10.1002/bbpc.19760800504 . [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]

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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]

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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]

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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]

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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]

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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]

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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]

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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]

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Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Mass spectrum (electron ionization), Vibrational and/or electronic energy levels, References

• Symbols used in this document:
  

  Cp,gas	Constant pressure heat capacity of gas
  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
  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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