Hydrogen cyanide

• Formula: CHN
• Molecular weight: 27.0253
• IUPAC Standard InChI: InChI=1S/CHN/c1-2/h1H Copy

  
• IUPAC Standard InChIKey: LELOWRISYMNNSU-UHFFFAOYSA-N Copy
• CAS Registry Number: 74-90-8
• Chemical structure:
  This structure is also available as a 2d Mol file
• Other names: Hydrocyanic acid; AC; Blausaeure (German); Carbon hydride nitride (CHN); Formic anammonide; Formonitrile; HCN; Prussic Acid; Cyclon; Acide cyanhydrique; Acido cianidrico; Aero Liquid HCN; Blausaeure; Blauwzuur; Cyaanwaterstof; Cyanwasserstoff; Cyclone B; Cyjanowodor; Evercyn; NA 1051; Prussic acid, unstabilized; Rcra waste number P063; UN 1051; Zaclondiscoids; Carbon hydride nitride; Zootic acid; Agent AC; Nitrilomethane
• 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 (reactions 1 to 50)
  • Gas phase ion energetics data
  • Mass spectrum (electron ionization)
  • References
  • Notes
• Other data available:
  • Condensed phase thermochemistry data
  • Phase change data
  • Reaction thermochemistry data: reactions 51 to 92
  • Henry's Law data
  • Ion clustering data
  • IR Spectrum
  • Vibrational and/or electronic energy levels
  • Gas Chromatography
• Data at other public NIST sites:
  • Microwave spectra (on physics lab web site)
  • Gas Phase Kinetics Database
• Options:
  • Switch to calorie-based units

Data at NIST subscription sites:

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

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.

Gas phase thermochemistry data

Go To: Top, Reaction thermochemistry 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.

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.

View plot Requires a JavaScript / HTML 5 canvas capable browser.

View table.

Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry 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:
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. 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.

Reactions 1 to 50

CN^- +  = (CN^- • )

By formula: CN^- + CHN = (CN^- • CHN)

 +  = ( • )

By formula: F^- + CHN = (F^- • CHN)

 +  = ( • )

By formula: Li⁺ + CHN = (Li⁺ • CHN)

 +  = ( • )

By formula: Cl^- + CHN = (Cl^- • CHN)

CN^- +  =

By formula: CN^- + H⁺ = CHN

 +  = ( • )

By formula: CHO₂^- + CHN = (CHO₂^- • CHN)

Free energy of reaction

( • ) +  = ( • 2)

By formula: (CHO₂^- • CHN) + CHN = (CHO₂^- • 2CHN)

Free energy of reaction

( • 3 • ) +  = ( • 4 • )

By formula: (H₄N⁺ • 3CHN • H₃N) + CHN = (H₄N⁺ • 4CHN • H₃N)

Free energy of reaction

( • 8) +  = ( • 9)

By formula: (Cl^- • 8CHN) + CHN = (Cl^- • 9CHN)

Free energy of reaction

( • 4) +  = ( • 5)

By formula: (C₂H₃O₂^- • 4CHN) + CHN = (C₂H₃O₂^- • 5CHN)

Free energy of reaction

(CN^- • 6) +  = (CN^- • 7)

By formula: (CN^- • 6CHN) + CHN = (CN^- • 7CHN)

Free energy of reaction

(CN^- • 2) +  = (CN^- • 3)

By formula: (CN^- • 2CHN) + CHN = (CN^- • 3CHN)

(CN^- • 3) +  = (CN^- • 4)

By formula: (CN^- • 3CHN) + CHN = (CN^- • 4CHN)

(CN^- • ) +  = (CN^- • 2)

By formula: (CN^- • CHN) + CHN = (CN^- • 2CHN)

CH₂N⁺ +  = (CH₂N⁺ • )

By formula: CH₂N⁺ + CHN = (CH₂N⁺ • CHN)

(CN^- •  • 2) +  = (CN^- • 2 • 2)

By formula: (CN^- • H₂O • 2CHN) + H₂O = (CN^- • 2H₂O • 2CHN)

Free energy of reaction

(CN^- • 3) +  = (CN^- •  • 3)

By formula: (CN^- • 3CHN) + H₂O = (CN^- • H₂O • 3CHN)

Free energy of reaction

(CH₂N⁺ •  • ) +  = (CH₂N⁺ • 2 • )

By formula: (CH₂N⁺ • CHN • H₂O) + CHN = (CH₂N⁺ • 2CHN • H₂O)

( •  • 2) +  = ( • 2 • 2)

By formula: (H₄N⁺ • H₃N • 2CHN) + H₃N = (H₄N⁺ • 2H₃N • 2CHN)

Free energy of reaction

( •  • 2) +  = ( • 2 • 2)

By formula: (H₄N⁺ • CHN • 2H₃N) + CHN = (H₄N⁺ • 2CHN • 2H₃N)

Free energy of reaction

(CN^- • 4) +  = (CN^- • 5)

By formula: (CN^- • 4CHN) + CHN = (CN^- • 5CHN)

( • ) +  = ( •  • )

By formula: (H₄N⁺ • CHN) + H₃N = (H₄N⁺ • H₃N • CHN)

Free energy of reaction

 +  = ( • )

By formula: Br^- + CHN = (Br^- • CHN)

C₄H₉O₂⁺ +  = (C₄H₉O₂⁺ • )

By formula: C₄H₉O₂⁺ + CHN = (C₄H₉O₂⁺ • CHN)

Free energy of reaction

C₃H₇⁺ +  = (C₃H₇⁺ • )

By formula: C₃H₇⁺ + CHN = (C₃H₇⁺ • CHN)

HS^- +  = (HS^- • )

By formula: HS^- + CHN = (HS^- • CHN)

 +  = ( • )

By formula: H₄N⁺ + CHN = (H₄N⁺ • CHN)

(CN^- •  • ) +  = (CN^- • 2 • )

By formula: (CN^- • H₂O • CHN) + H₂O = (CN^- • 2H₂O • CHN)

(CN^- • 2) +  = (CN^- •  • 2)

By formula: (CN^- • 2CHN) + H₂O = (CN^- • H₂O • 2CHN)

(CN^- • ) +  = (CN^- •  • )

By formula: (CN^- • CHN) + H₂O = (CN^- • H₂O • CHN)

( • 7) +  = ( • 8)

By formula: (Cl^- • 7CHN) + CHN = (Cl^- • 8CHN)

(CN^- •  • 2) +  = (CN^- • 2 • 2)

By formula: (CN^- • CHN • 2H₂O) + CHN = (CN^- • 2CHN • 2H₂O)

Free energy of reaction

(CN^- • 2 • ) +  = (CN^- • 3 • )

By formula: (CN^- • 2CHN • H₂O) + CHN = (CN^- • 3CHN • H₂O)

Free energy of reaction

( • 2) +  = ( • 3)

By formula: (Cl^- • 2CHN) + CHN = (Cl^- • 3CHN)

( • 3) +  = ( • 4)

By formula: (Cl^- • 3CHN) + CHN = (Cl^- • 4CHN)

( • ) +  = ( • 2)

By formula: (Cl^- • CHN) + CHN = (Cl^- • 2CHN)

( • 2) +  = ( • 3)

By formula: (I^- • 2CHN) + CHN = (I^- • 3CHN)

( • 2) +  = ( • 3)

By formula: (Br^- • 2CHN) + CHN = (Br^- • 3CHN)

( • 3) +  = ( • 4)

By formula: (Br^- • 3CHN) + CHN = (Br^- • 4CHN)

( • 4) +  = ( • 5)

By formula: (Cl^- • 4CHN) + CHN = (Cl^- • 5CHN)

( • 5) +  = ( • 6)

By formula: (Cl^- • 5CHN) + CHN = (Cl^- • 6CHN)

( • 6) +  = ( • 7)

By formula: (Cl^- • 6CHN) + CHN = (Cl^- • 7CHN)

( • 3) +  = ( • 4)

By formula: (I^- • 3CHN) + CHN = (I^- • 4CHN)

( • 4) +  = ( • 5)

By formula: (I^- • 4CHN) + CHN = (I^- • 5CHN)

( • 5) +  = ( • 6)

By formula: (I^- • 5CHN) + CHN = (I^- • 6CHN)

( • 6) +  = ( • 7)

By formula: (I^- • 6CHN) + CHN = (I^- • 7CHN)

( • 7) +  = ( • 8)

By formula: (I^- • 7CHN) + CHN = (I^- • 8CHN)

( • ) +  = ( • 2)

By formula: (I^- • CHN) + CHN = (I^- • 2CHN)

( • 4) +  = ( • 5)

By formula: (Br^- • 4CHN) + CHN = (Br^- • 5CHN)

( • ) +  = ( • 2)

By formula: (Br^- • CHN) + CHN = (Br^- • 2CHN)

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry 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 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 CHN⁺ (ion structure unspecified)

Electron affinity determinations

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

CN^- +  =

By formula: CN^- + H⁺ = CHN

Mass spectrum (electron ionization)

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry 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 by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Spectrum

Notice: This spectrum may be better viewed with a Javascript and HTML 5 enabled browser.

For Zoom

1.) Enter the desired X axis range (e.g., 100, 200)

2.) Check here for automatic Y scaling

3.) Press here to zoom

Additional Data

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics 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.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Larson and McMahon, 1987
Larson, J.W.; McMahon, T.B., Hydrogen bonding in gas phase anions. The energetics of interaction between cyanide ion and bronsted acids, J. Am. Chem. Soc., 1987, 109, 6230. [all data]

Larson and McMahon, 1984
Larson, J.W.; McMahon, T.B., Gas phase bihalide and pseudohalide ions. An ICR determination of hydrogen bond energies in XHY- species (X,Y = F, Cl, Br, CN), Inorg. Chem., 1984, 23, 2029. [all data]

Meot-Ner (Mautner) and Speller, 1989
Meot-Ner (Mautner), M.; Speller, C.V., Multicomponent Cluster Ions.3. Comparative Stabilities of Cationic and Anionic Hydrogen Bonded Networks. Mixed Clusters of Water and Hydrogen Cyanide, J. Phys. Chem., 1989, 93, 6580. [all data]

Meot-ner, 1988
Meot-ner, M., Ionic Hydrogen Bond and Ion Solvation. ₆. Interaction Energies of the Acetate Ion with Organic Molecules. Comparison of CH₃COO^- with Cl^-, CN^-, and SH^-, J. Am. Chem. Soc., 1988, 110, 12, 3854, https://doi.org/10.1021/ja00220a022 . [all data]

Meot-ner, Cybulski, et al., 1988
Meot-ner, M.; Cybulski, S.M.; Scheiner, S.; Liebman, J.F., Is CN^- Significantly Anisotropic? Comparison of CN^- vs. Cl^-: Clustering with HCN and Condensed Phase Thermochemistry, J. Phys. Chem., 1988, 92, 10, 2738, https://doi.org/10.1021/j100321a009 . [all data]

Payzant, Yamdagni, et al., 1971
Payzant, J.D.; Yamdagni, R.; Kebarle, P., Hydration of CN-, NO₂-, NO₃-, and HO- in the gas phase, Can. J. Chem., 1971, 49, 3308. [all data]

Larson and McMahon, 1983
Larson, J.W.; McMahon, T.B., Strong hydrogen bonding in gas-phase anions. An ion cyclotron resonance determination of fluoride binding energetics to bronsted acids from gas-phase fluoride exchange equilibria measurements, J. Am. Chem. Soc., 1983, 105, 2944. [all data]

Wenthold and Squires, 1995
Wenthold, P.G.; Squires, R.R., Bond dissociation energies of F2(-) and HF2(-). A gas-phase experimental and G2 theoretical study, J. Phys. Chem., 1995, 99, 7, 2002, https://doi.org/10.1021/j100007a034 . [all data]

Arshadi, Yamdagni, et al., 1970
Arshadi, M.; Yamdagni, R.; Kebarle, P., Hydration of Halide Negative Ions in the Gas Phase. II. Comparison of Hydration Energies for the Alkali Positive and Halide Negative Ions, J. Phys. Chem., 1970, 74, 7, 1475, https://doi.org/10.1021/j100702a014 . [all data]

Woodin and Beauchamp, 1978
Woodin, R.L.; Beauchamp, J.L., Bonding of Li+ to Lewis Bases in the Gas Phase. Reversals in Methyl Substituent Effects for Different Reference Acids, J. Am. Chem. Soc., 1978, 100, 2, 501, https://doi.org/10.1021/ja00470a024 . [all data]

Dzidic and Kebarle, 1970
Dzidic, I.; Kebarle, P., Hydration of the Alkali Ions in the Gas Phase. Enthalpies and Entropies of Reactions M+(H2O)n-1 + H2O = M+(H2O)n, J. Phys. Chem., 1970, 74, 7, 1466, https://doi.org/10.1021/j100702a013 . [all data]

Staley and Beauchamp, 1975
Staley, R.H.; Beauchamp, J.L., Intrinsic Acid - Base Properties of Molecules. Binding Energies of Li+ to pi - and n - Donor Bases, J. Am. Chem. Soc., 1975, 97, 20, 5920, https://doi.org/10.1021/ja00853a050 . [all data]

Larson and McMahon, 1984, 2
Larson, J.W.; McMahon, T.B., Hydrogen bonding in gas phase anions. An experimental investigation of the interaction between chloride ion and bronsted acids from ICR chloride exchange equilibria, J. Am. Chem. Soc., 1984, 106, 517. [all data]

Larson and McMahon, 1984, 3
Larson, J.W.; McMahon, T.B., Gas phase negative ion chemistry of alkylchloroformates, Can. J. Chem., 1984, 62, 675. [all data]

French, Ikuta, et al., 1982
French, M.A.; Ikuta, S.; Kebarle, P., Hydrogen bonding of O-H and C-H hydrogen donors to Cl^-. Results from mass spectrometric measurement of the ion-molecule equilibria RH + Cl^- = RHCl^-, Can. J. Chem., 1982, 60, 1907. [all data]

Akin and Ervin, 2006
Akin, F.A.; Ervin, K.M., Collision-induced dissociation of HS-(HCN): Unsymmetrical hydrogen bonding in a proton-bound dimer anion, J. Phys. Chem. A, 2006, 110, 4, 1342-1349, https://doi.org/10.1021/jp0540454 . [all data]

Bradforth, Kim, et al., 1993
Bradforth, S.E.; Kim, E.H.; Arnold, D.W.; Neumark, D.M., Photoelectron Spectroscopy of CN-, NCO-, and NCS-, J. Chem. Phys., 1993, 98, 2, 800, https://doi.org/10.1063/1.464244 . [all data]

Bartmess, Scott, et al., 1979
Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr., The gas phase acidity scale from methanol to phenol, J. Am. Chem. Soc., 1979, 101, 6047. [all data]

Deakyne, Knuth, et al., 1994
Deakyne, C.A.; Knuth, D.M.; Speller, C.V.; Meot-Ner (Mautner), M.; Sieck, L.W., Filling of Solvent Shells about Ions. Part 3. Isomeric Clusters of (HCN)n(NH3)mH+, J. Mol. Structure (Theochem), 1994, 307, 217, https://doi.org/10.1016/0166-1280(94)80130-4 . [all data]

Speller and Meot-Ner (Mautner), 1985
Speller, C.V.; Meot-Ner (Mautner), M., The Ionic Hydrogen Bond and Ion Solvation. 3. Bonds Involving Cyanides. Correlations with Proton Affinites, J. Phys. Chem., 1985, 81, 24, 5217, https://doi.org/10.1021/j100270a020 . [all data]

Meot-Ner (Mautner), 1978
Meot-Ner (Mautner), M., Solvation of the Proton by HCN and CH3CN. Condensation of HCN with Ions in the Gas Phase., J. Am. Chem. Soc., 1978, 100, 15, 4694, https://doi.org/10.1021/ja00483a012 . [all data]

Meot-Ner (Mautner) M. and Speller, 1989
Meot-Ner (Mautner) M.; Speller, C.V., Multicomponent Cluster Ions. 2. Comparative Stabilities of Cationic and Anionic Hydrogen Bonded Networks. Mixed Clusters of Water and Hydrogen Cyanide, J. Phys. Chem., 1989, 93, 9, 3663, https://doi.org/10.1021/j100346a058 . [all data]

Meot-Ner (Mautner) and Sieck, 1991
Meot-Ner (Mautner), M.; Sieck, L.W., Proton affinity ladders from variable-temperature equilibrium measurements. 1. A reevaluation of the upper proton affinity range, J. Am. Chem. Soc., 1991, 113, 12, 4448, https://doi.org/10.1021/ja00012a012 . [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]

Ard, Garrett, et al., 2009
Ard, S.; Garrett, W.R.; Compton, R.N.; Adamowicz, L.; Stepanian, S.G., Rotational states of dipole-bound anions of hydrogen cyanide., Chem. Phys. Lett., 2009, 473, 4-6, 223, https://doi.org/10.1016/j.cplett.2009.04.007 . [all data]

Tsuda, Yokohata, et al., 1971
Tsuda, S.; Yokohata, A.; Umaba, T., Measurement of negative ions formed by electron impact. VIII. Ionization efficiency curves of negative ions from methyl and ethyl cyanides, Bull. Chem. Soc. Jpn., 1971, 44, 1486. [all data]

Lageot, 1972
Lageot, C., Etude des etats excites de l'ion HCN⁺, J. Chim. Phys. Phys.-Chim. Biol., 1972, 68, 214. [all data]

Dibeler and Liston, 1968
Dibeler, V.H.; Liston, S.K., Mass-spectrometric study of photoionization. IX. Hydrogen cyanide and acetonitrile, J. Chem. Phys., 1968, 48, 4765. [all data]

Baker and Turner, 1968
Baker, C.; Turner, D.W., High resolution molecular photoelectron spectroscopy. III.Acetylenes and azaacetylenes, Proc. Roy. Soc. (London), 1968, A308, 19. [all data]

Varsel, Morrell, et al., 1960
Varsel, C.J.; Morrell, F.A.; Resnik, F.E.; Powell, W.A., Qualitative and quantitative analysis of organic compounds. Use of low-voltage mass spectrometry, Anal. Chem., 1960, 32, 182. [all data]

Kusch, Hustrulid, et al., 1937
Kusch, P.; Hustrulid, A.; Tate, J.T., The dissociation of HCN, C₂H₂, C₂N₂ and C₂H₄ by electron impact, Phys. Rev., 1937, 52, 843. [all data]

Kreile, Schweig, et al., 1982
Kreile, J.; Schweig, A.; Thiel, W., Experimental and theoretical investigation of the photoionization of hydrogen cyanide, Chem. Phys. Lett., 1982, 87, 473. [all data]

Fridh and Asbrink, 1975
Fridh, C.; Asbrink, L., Photoelectron electron impact spectrum of HCN, J. Electron Spectrosc. Relat. Phenom., 1975, 7, 119. [all data]

Potts and Williams, 1974
Potts, A.W.; Williams, T.A., The observation of "forbidden" transitions in He II photoelectron spectra, J. Electron Spectrosc. Relat. Phenom., 1974, 3, 3. [all data]

Frost, Lee, et al., 1973
Frost, D.C.; Lee, S.T.; McDowell, C.A., The photoelectron spectrum of HCP and comments on the first photoelectron band of HCN, Chem. Phys. Lett., 1973, 23, 472. [all data]

Berkowitz, Chupka, et al., 1969
Berkowitz, J.; Chupka, W.A.; Walter, T.A., Photoionization of HCN: the electron affinity and heat of formation of CN, J. Chem. Phys., 1969, 50, 1497. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), References

• Symbols used in this document:
  

  AE	Appearance energy
  EA	Electron affinity
  IE (evaluated)	Recommended ionization energy
  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
  ΔrS°	Entropy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
• The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
• Customer support for NIST Standard Reference Data products.