Chlorine

• Formula: Cl₂
• Molecular weight: 70.906
• IUPAC Standard InChI: InChI=1S/Cl2/c1-2 Copy

  
• IUPAC Standard InChIKey: KZBUYRJDOAKODT-UHFFFAOYSA-N Copy
• CAS Registry Number: 7782-50-5
• 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: Cl2; Bertholite; Chloor; Chlor; Chlore; Chlorine mol.; Cloro; Molecular chlorine; UN 1017; Diatomic chlorine
• 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
  • Mass spectrum (electron ionization)
  • Constants of diatomic molecules
  • References
  • Notes
• Other data available:
  • Reaction thermochemistry data
  • Ion clustering data
• Data at other public NIST sites:
  • Gas Phase Kinetics Database
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Gas phase thermochemistry data

Go To: Top, Phase change data, Henry's Law data, Gas phase ion energetics data, Mass spectrum (electron ionization), Constants of diatomic molecules, 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 (cal/mol*K)
    H° = standard enthalpy (kcal/mol)
    S° = standard entropy (cal/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:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director

Antoine Equation Parameters

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

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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, Mass spectrum (electron ionization), Constants of diatomic molecules, 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:
LL - Sharon G. Lias and Joel F. Liebman
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
B - John E. Bartmess

View reactions leading to Cl₂⁺ (ion structure unspecified)

Electron affinity determinations

Ionization energy determinations

Appearance energy determinations

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

Constants of diatomic molecules

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 by: Klaus P. Huber and Gerhard H. Herzberg

Data collected through September, 1976

Notes

References

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

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

Cox, Wagman, et al., 1984
Cox, J.D.; Wagman, D.D.; Medvedev, V.A., CODATA Key Values for Thermodynamics, Hemisphere Publishing Corp., New York, 1984, 1. [all data]

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

Thiele and Schulte, 1920
Thiele, A.; Schulte, E., Binary equilibrium systems with solid carbon dioxide, Z. Phys. Chem., Stoechiom. Verwandtschaftsl., 1920, 96, 312-42. [all data]

Angus, Armstrong, et al., 1984
Angus, S.; Armstrong, B.; de Reuck, K.M., International Thermodynamic Tables of the Fluid State - Chlorine, Pergamon, Oxford, 1984. [all data]

Giauque and Powell, 1939
Giauque, W.F.; Powell, T.M., Chlorine. The Heat Capacity, Vapor Pressure, Heats of Fusion and Vaporiza- tion, and Entropy, J. Am. Chem. Soc., 1939, 61, 1970. [all data]

Ambrose, Hall, et al., 1979
Ambrose, D.; Hall, D.J.; Lee, D.A.; Lewis, G.B., Vapor pressure of chlorine, J. Chem. Thermodyn., 1979, 11, 1089. [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]

Bowen, Liesegang, et al., 1983
Bowen, K.H.; Liesegang, G.W.; Sanders, R.A.; Herschbach, D.W., Electron Attachment to Molecular Clusters by Collisional Charge Transfer, J. Phys. Chem., 1983, 87, 4, 557-565, https://doi.org/10.1021/j100227a009 . [all data]

Ayala, Wentworth, et al., 1981
Ayala, J.A.; Wentworth, W.E.; Chen, E.C.M., Electron attachment to halogens, J. Phys. Chem., 1981, 85, 768. [all data]

Dispert and Lacmann, 1977
Dispert, H.; Lacmann, K., Chemiionization in alkali-halogen reactions: Evidence for ion formation by alkali dimers, Chem. Phys. Lett., 1977, 47, 533. [all data]

Hughes, Lifschitz, et al., 1973
Hughes, B.M.; Lifschitz, C.; Tiernan, T.O., Electron affinities from endothermic negative-ion charge-transfer reactions. III. NO, NO₂, S₂, CS₂, Cl₂, Br₂, I₂, and C₂H, J. Chem. Phys., 1973, 59, 3162. [all data]

Baeda, 1972
Baeda, A.P.M., The adiabatic electron affinities of Cl₂, Br₂, I₂, IBr, NO₂, and O₂, Physica, 1972, 59, 541. [all data]

Dunkin, Fehsenfeld, et al., 1972
Dunkin, D.B.; Fehsenfeld, F.C.; Ferguson, F.E., Thermal energy rate constants for the reactions NO₂^- + Cl₂ → Cl₂^-, Cl₂^- + NO₂ Ü Cl^-, HS^- + NO₂ Ü NO₂^-, HS^- + Cl₂ Ü Cl₂^-, and S^- + NO₂ Ü NO₂^-, Chem. Phys. Lett., 1972, 15, 257. [all data]

Chupka, Berkowitz, et al., 1971
Chupka, W.A.; Berkowitz, J.; Gutman, D., Electron Affinities of Halogen Diatomic Molecules as Determined by Endoergic Charge Exchange, J. Chem. Phys., 1971, 55, 6, 2724, https://doi.org/10.1063/1.1676487 . [all data]

DeCorpo and Franklin, 1971
DeCorpo, J.J.; Franklin, J.L., Electron affinities of the halogen molecules by dissociative electron attachment, J. Chem. Phys., 1971, 54, 1885. [all data]

Hubers, Kleyn, et al., 1976
Hubers, M.M.; Kleyn, A.W.; Los, J., Ion pair formation in alkali-halogen collisions at high velocities, Chem. Phys., 1976, 17, 303. [all data]

Lacmann and Herschbach, 1970
Lacmann, K.; Herschbach, D.R., Collisional Excitation and Ionization of K Atoms by Diatomic Molecules: Role of Ion-pair States, Chem. Phys. Lett., 1970, 6, 2, 106, https://doi.org/10.1016/0009-2614(70)80144-0 . [all data]

Yencha, Hopkirk, et al., 1995
Yencha, A.J.; Hopkirk, A.; Hiraya, A.; Donovan, R.J.; Goode, J.G.; Maier, R.R.J.; King, G.C.; Kvaran, A., Threshold photoelectron spectroscopy of Cl₂ and Br₂ up to 35 eV, J. Phys. Chem., 1995, 99, 7231. [all data]

Van Lonkhuyzen and De Lange, 1984
Van Lonkhuyzen, H.; De Lange, C.A., High-resolution UV photoelectron spectroscopy of diatomic halogens, Chem. Phys., 1984, 89, 313. [all data]

Huber and Herzberg, 1979
Huber, K.P.; Herzberg, G., Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules,, Van Nostrand Reinhold Co., 1979, ,1. [all data]

Potts and Price, 1971
Potts, A.W.; Price, W.C., Photoelectron spectra of the halogens and mixed halides ICI and lBr, J. Chem. Soc. Faraday Trans., 1971, 67, 1242. [all data]

Dibeler, Walker, et al., 1971
Dibeler, V.H.; Walker, J.A.; McCulloh, K.E.; Rosenstock, H.M., Effect of hot bands on the ionization threshold of some diatomic halogen molecules, Intern. J. Mass Spectrom. Ion Phys., 1971, 7, 209. [all data]

Cornford, Frost, et al., 1971
Cornford, A.B.; Frost, D.C.; McDowell, C.A.; Ragle, J.L.; Stenhouse, I.A., Photoelectron spectra of the halogens, J. Chem. Phys., 1971, 54, 2651. [all data]

Anderson, Mamantov, et al., 1971
Anderson, C.P.; Mamantov, G.; Bull, W.E.; Grimm, F.A.; Carver, J.C.; Carlson, T.A., Photoelectron spectrum of chlorine monofluoride, Chem. Phys. Lett., 1971, 12, 137. [all data]

Watanabe, 1957
Watanabe, K., Ionization potentials of some molecules, J. Chem. Phys., 1957, 26, 542. [all data]

Dyke, Josland, et al., 1984
Dyke, J.M.; Josland, G.D.; Snijders, J.G.; Boerrigter, P.M., Ionization energies of the diatomic halogens and interhalogens studied with relativistic hartree-fock-slater calculations, Chem. Phys., 1984, 91, 419. [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Frost and McDowell, 1959
Frost, D.C.; McDowell, C.A., Recent electron impact studies on simple molecules (O₂, Cl₂, I₂), Advan. Mass Spectrom., 1959, 1, 413. [all data]

Iczkowski, Margrave, et al., 1960
Iczkowski, R.P.; Margrave, J.L.; Green, J.W., Absorption spectrum of chlorine in the vacuum ultraviolet, J. Chem. Phys., 1960, 33, 1261. [all data]

Lee and Walsh, 1959
Lee, J.; Walsh, A.D., The vacuum ultra-violet absorption spectra of the halogen molecules, Trans. Faraday Soc., 1959, 55, 1281. [all data]

Asundi and Venkateswarlu, 1947
Asundi, R.K.; Venkateswarlu, P., Spectra of the Halogens, I₂, Br₂ and Cl₂, Indian J. Phys., 1947, 21, 101-118. [all data]

Haranath and Rao, 1958
Haranath, P.B.V.; Rao, P.T., Band spectra of iodine, chlorine, and bromine in the spectral region 2400-1400 A, J. Mol. Spectrosc., 1958, 2, 428. [all data]

Khanna, 1959
Khanna, B.N., Emission spectrum of chlorine excited in the presence of argon, Proc. Indian Acad. Sci. Sect. A, 1959, 49, 293-301. [all data]

Venkateswarlu and Khanna, 1959
Venkateswarlu, P.; Khanna, B.N., Emission spectrum of chlorine excited in the presence of argon. Part I. The band system in the region 2600-2390 Å, Proc. Indian Acad. Sci. Sect. A, 1959, 49, 117-127. [all data]

Wieland, Tellinghuisen, et al., 1972
Wieland, K.; Tellinghuisen, J.B.; Nobs, A., The band systems E → B(4000-4360 Å) and F → X(2530-2740 Å) of ¹²⁷I₂ and ¹²⁹I₂, and the corresponding system E = B of Br₂ and Cl₂, J. Mol. Spectrosc., 1972, 41, 69. [all data]

Cordes and Sponer, 1930
Cordes, H.; Sponer, H., Die molekulabsorption des chlors, broms, jodchlorids und jodbromids im aubersten ultraviolett, Z. Phys., 1930, 63, 334. [all data]

Gibson and Bayliss, 1933
Gibson, G.E.; Bayliss, N.S., Variation with temperature of the continuous absorption spectrum of diatomic molecules: Part I. Experimental, the absorption spectrum of chlorine, Phys. Rev., 1933, 44, 188. [all data]

Sulzer and Wieland, 1952
Sulzer, P.; Wieland, K., Intensitatsverteilung eines kontinuierlichen Absorptions-spectrums in Abhangigkeit von Temperatur und Wellenzahl, Helv. Phys. Acta, 1952, 25, 653-676. [all data]

Jacobs and Giedt, 1965
Jacobs, T.A.; Giedt, R.R., Absorption coefficients of Cl₂ at high temperatures, J. Quant. Spectrosc. Radiat. Transfer, 1965, 5, 457. [all data]

Clyne and Stedman, 1968
Clyne, M.A.A.; Stedman, D.H., Recombination of ground-state halogen atoms. Part 1. Radiative recombination of chlorine atoms, Trans. Faraday Soc., 1968, 64, 1816. [all data]

Palmer and Carabetta, 1968
Palmer, H.B.; Carabetta, R.A., Radiative recombination of chlorine atoms in shock waves: a re-examination, J. Chem. Phys., 1968, 49, 2466. [all data]

Coxon, 1973
Coxon, J.A., Chapt. 4. Low-lying electronic states of diatomic halogen molecules in Molecular Spectroscopy. Volume 1, Barrow,R.F.; Long,D.A.; Millen,D.J., ed(s)., The Chemical Society, Burlington House, London, W1V 0BN, 1973, 177-228. [all data]

Bondybey and Fletcher, 1976
Bondybey, V.E.; Fletcher, C., Photophysics of low lying electronic states of Cl₂ in rare gas solids, J. Chem. Phys., 1976, 64, 3615. [all data]

Winkel, Hunt, et al., 1969
Winkel, R.G.; Hunt, J.L.; Clouter, M.J., Pressure-induced fundamental infrared absorption band of gaseous chlorine, J. Chem. Phys., 1969, 50, 1298. [all data]

Holzer, Murphy, et al., 1970
Holzer, W.; Murphy, W.F.; Bernstein, H.J., Resonance Raman effect and resonance fluoroscence in halogen gases, J. Chem. Phys., 1970, 52, 399. [all data]

Hochenbleicher and Schrotter, 1971
Hochenbleicher, G.; Schrotter, H.W., Observation of hot bands in the Raman spectra of Cl₂ gas and CCl₄ vapor, Appl. Spectrosc., 1971, 25, 3, 360-362. [all data]

Hendra and Vear, 1972
Hendra, P.J.; Vear, C.J., The pure rotational laser Raman spectrum of chlorine, Spectrochim. Acta, Part A, 1972, 28, 1949-1961. [all data]

Wallart, 1972
Wallart, F., Study of vibrational hot bands by Raman spectroscopy - application to chlorine and bromine chloride, Can. J. Spectrosc., 1972, 17, 128. [all data]

Edwards, Good, et al., 1976
Edwards, H.G.M.; Good, E.A.M.; Long, D.A., Pure rotational Raman spectra of the chlorine species, ³⁵Cl₂ and ³⁵Cl³⁷Cl, J. Chem. Soc. Faraday Trans. 2, 1976, 72, 927-933. [all data]

Rao and Venkateswarlu, 1962
Rao, Y.V.; Venkateswarlu, P., Vacuum ultraviolet resonance spectrum of Cl₂ molecule, J. Mol. Spectrosc., 1962, 9, 173. [all data]

Douglas and Hoy, 1975
Douglas, A.E.; Hoy, A.R., The resonance fluorescence spectrum of Cl₂ in the vacuum ultraviolet, Can. J. Phys., 1975, 53, 1965-1975. [all data]

Busch, Mahoney, et al., 1969
Busch, G.E.; Mahoney, R.T.; Morse, R.I., Translational spectroscopy: Cl₂ photodissociation, J. Chem. Phys., 1969, 51, 449. [all data]

Child and Bernstein, 1973
Child, M.S.; Bernstein, R.B., Diatomic interhalogens: systematics and implications of spectroscopic interatomic potentials and curve crossings, J. Chem. Phys., 1973, 59, 5916. [all data]

Brith, Rowe, et al., 1975
Brith, M.; Rowe, M.D.; Schnepp, O.; Stephens, P.J., The magnetic circular dichroism spectrum of the halogen molecules I₂, Br₂, Cl₂. Resolution of overlapping continua, Chem. Phys., 1975, 9, 57. [all data]

Douglas, Moller, et al., 1963
Douglas, A.E.; Moller, C.K.; Stoicheff, B.P., Can. J. Phys., 1963, 41, 1174. [all data]

Clyne and Coxon, 1970
Clyne, M.A.A.; Coxon, J.A., The visible band absorption spectrum of chlorine, J. Mol. Spectrosc., 1970, 33, 381. [all data]

Clyne and Coxon, 1967
Clyne, M.A.A.; Coxon, J.A., The formation and detection of some low-lying excited electronic states of BrCl and other halogens, Proc. R. Soc. London A, 1967, 298, 424. [all data]

Richards and Barrow, 1962
Richards, W.G.; Barrow, R.F., Rotational analysis of the A³Π_0+,u - X¹Σ_g⁺ system of the chlorine molecule, Proc. Chem. Soc. London, 1962, 297. [all data]

Le Roy, 1973
Le Roy, R.J., Chapt. 3. Energy levels of a diatomic near dissociation in Molecular Spectroscopy. Volume 1, Barrow,R.F.; Long,D.A.; Millen,D.J., ed(s)., The Chemical Society, Burlington House, London, W1V 0BN, 1973, 113-175. [all data]

LeRoy, 1974
LeRoy, R.J., Long-range potential coefficients from RKR turning points: C₆ and C₈ for B(³Π_0u⁺)-state Cl₂, Br₂, and I₂, Can. J. Phys., 1974, 52, 246. [all data]

LeRoy and Bernstein, 1971
LeRoy, R.J.; Bernstein, R.B., Dissociation energies and long-range potentials of diatomic molecules from vibrational spacings: the halogens, J. Mol. Spectrosc., 1971, 37, 109. [all data]

Goscinski, 1972
Goscinski, O., Outer vibrational turning points near dissociation in the B(³Π_0u⁺) state of Br₂ and Cl₂, Mol. Phys., 1972, 24, 655. [all data]

LeRoy, 1972
LeRoy, R.J., Dependence of the diatomic rotational constant B_v on the long-range internuclear potential, Can. J. Phys., 1972, 50, 953. [all data]

Yee and Stone, 1973
Yee, K.K.; Stone, T.J., Analysis of RKR long-range potentials of the B³Π_0u+ states of Br₂ and Cl₂, Mol. Phys., 1973, 26, 1169. [all data]

Coxon, 1971
Coxon, J.A., Franck-Condon factors and r-centroids for halogen molecules. I. The B³Π(0_u⁺)-X¹Σ_g⁺ system of ³⁵Cl₂, J. Quant. Spectrosc. Radiat. Transfer, 1971, 11, 1355. [all data]

Ault, Howard, et al., 1975
Ault, B.S.; Howard, W.F.; Andrews, L., Laser-induced fluorescence and Raman spectra of chlorine and bromine molecules isolated in inert matrices, J. Mol. Spectrosc., 1975, 55, 217. [all data]

Radziemski and Kaufman, 1969
Radziemski, L.J., Jr.; Kaufman, V., Wavelengths, energy levels, and analysis of neutral atomic chlorine (Cl I), J. Opt. Soc. Am., 1969, 59, 4, 424-443. [all data]

Watanabe, Nakayama, et al., 1962
Watanabe, K.; Nakayama, T.; Mottl, J., Ionization potentials of some molecules, J. Quant. Spectry. Radiative Transfer, 1962, 2, 369. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, Mass spectrum (electron ionization), Constants of diatomic molecules, References

• Symbols used in this document:
  

  AE	Appearance energy
  EA	Electron affinity
  Pc	Critical pressure
  Ptriple	Triple point pressure
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  Tboil	Boiling point
  Tc	Critical temperature
  Ttriple	Triple point temperature
  d(ln(kH))/d(1/T)	Temperature dependence parameter for Henry's Law constant
  k°H	Henry's Law constant at 298.15K
  ρc	Critical density

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