Hydrogen

• Formula: H₂
• Molecular weight: 2.01588
• IUPAC Standard InChI: InChI=1S/H2/h1H Copy

  
• IUPAC Standard InChIKey: UFHFLCQGNIYNRP-UHFFFAOYSA-N Copy
• CAS Registry Number: 1333-74-0
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  View 3d structure (requires JavaScript / HTML 5)
• Isotopologues:
  • tritium
  • deuterium hydride
  • Deuterium
• Other names: Dihydrogen; o-Hydrogen; p-Hydrogen; Molecular hydrogen; H2; UN 1049; UN 1966
• 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
  • Ion clustering data
  • References
  • Notes
• Other data available:
  • Reaction thermochemistry data: reactions 1 to 50, reactions 51 to 100, reactions 101 to 150, reactions 151 to 200, reactions 201 to 250, reactions 251 to 300, reactions 301 to 350, reactions 351 to 400, reactions 401 to 450, reactions 451 to 500, reactions 501 to 550, reactions 551 to 600, reactions 601 to 621
  • Gas phase ion energetics data
  • Mass spectrum (electron ionization)
  • Constants of diatomic molecules
  • Fluid Properties
• Data at other public NIST sites:
  • 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, Phase change data, Henry's Law 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.

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)

Ion clustering data

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law 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: 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

Ar⁺ +  = (Ar⁺ • )

By formula: Ar⁺ + H₂ = (Ar⁺ • H₂)

 +  = ( • )

By formula: CHO⁺ + H₂ = (CHO⁺ • H₂)

CH₅⁺ +  = (CH₅⁺ • )

By formula: CH₅⁺ + H₂ = (CH₅⁺ • H₂)

(CH₅⁺ • ) +  = (CH₅⁺ • 2)

By formula: (CH₅⁺ • H₂) + H₂ = (CH₅⁺ • 2H₂)

(CH₅⁺ • 2) +  = (CH₅⁺ • 3)

By formula: (CH₅⁺ • 2H₂) + H₂ = (CH₅⁺ • 3H₂)

(CH₅⁺ • 3) +  = (CH₅⁺ • 4)

By formula: (CH₅⁺ • 3H₂) + H₂ = (CH₅⁺ • 4H₂)

C₃H₇⁺ +  = (C₃H₇⁺ • )

By formula: C₃H₇⁺ + H₂ = (C₃H₇⁺ • H₂)

Free energy of reaction

( • ) +  = ( •  • )

By formula: (Co⁺ • CH₄) + H₂ = (Co⁺ • H₂ • CH₄)

Enthalpy of reaction

( • ) +  = ( •  • )

By formula: (Co⁺ • H₂O) + H₂ = (Co⁺ • H₂ • H₂O)

Enthalpy of reaction

 +  = ( • )

By formula: Co⁺ + H₂ = (Co⁺ • H₂)

Enthalpy of reaction

( • ) +  = ( • 2)

By formula: (Co⁺ • H₂) + H₂ = (Co⁺ • 2H₂)

( • 2) +  = ( • 3)

By formula: (Co⁺ • 2H₂) + H₂ = (Co⁺ • 3H₂)

( • 3) +  = ( • 4)

By formula: (Co⁺ • 3H₂) + H₂ = (Co⁺ • 4H₂)

( • 4) +  = ( • 5)

By formula: (Co⁺ • 4H₂) + H₂ = (Co⁺ • 5H₂)

( • 5) +  = ( • 6)

By formula: (Co⁺ • 5H₂) + H₂ = (Co⁺ • 6H₂)

( • 6) +  = ( • 7)

By formula: (Co⁺ • 6H₂) + H₂ = (Co⁺ • 7H₂)

 +  = ( • )

By formula: Fe⁺ + H₂ = (Fe⁺ • H₂)

( • ) +  = ( • 2)

By formula: (Fe⁺ • H₂) + H₂ = (Fe⁺ • 2H₂)

( • 2) +  = ( • 3)

By formula: (Fe⁺ • 2H₂) + H₂ = (Fe⁺ • 3H₂)

( • 3) +  = ( • 4)

By formula: (Fe⁺ • 3H₂) + H₂ = (Fe⁺ • 4H₂)

( • 4) +  = ( • 5)

By formula: (Fe⁺ • 4H₂) + H₂ = (Fe⁺ • 5H₂)

( • 5) +  = ( • 6)

By formula: (Fe⁺ • 5H₂) + H₂ = (Fe⁺ • 6H₂)

HN₂⁺ +  = (HN₂⁺ • )

By formula: HN₂⁺ + H₂ = (HN₂⁺ • H₂)

(HN₂⁺ • ) +  = (HN₂⁺ • 2)

By formula: (HN₂⁺ • H₂) + H₂ = (HN₂⁺ • 2H₂)

 +  = ( • )

By formula: HO^- + H₂ = (HO^- • H₂)

HO₂⁺ +  = (HO₂⁺ • )

By formula: HO₂⁺ + H₂ = (HO₂⁺ • H₂)

(HO₂⁺ • ) +  = (HO₂⁺ •  • )

By formula: (HO₂⁺ • O₂) + H₂ = (HO₂⁺ • H₂ • O₂)

H₃⁺ +  = (H₃⁺ • )

By formula: H₃⁺ + H₂ = (H₃⁺ • H₂)

(H₃⁺ • ) +  = (H₃⁺ • 2)

By formula: (H₃⁺ • H₂) + H₂ = (H₃⁺ • 2H₂)

(H₃⁺ • 2) +  = (H₃⁺ • 3)

By formula: (H₃⁺ • 2H₂) + H₂ = (H₃⁺ • 3H₂)

(H₃⁺ • 3) +  = (H₃⁺ • 4)

By formula: (H₃⁺ • 3H₂) + H₂ = (H₃⁺ • 4H₂)

(H₃⁺ • 4) +  = (H₃⁺ • 5)

By formula: (H₃⁺ • 4H₂) + H₂ = (H₃⁺ • 5H₂)

(H₃⁺ • 5) +  = (H₃⁺ • 6)

By formula: (H₃⁺ • 5H₂) + H₂ = (H₃⁺ • 6H₂)

(H₃⁺ • 6) +  = (H₃⁺ • 7)

By formula: (H₃⁺ • 6H₂) + H₂ = (H₃⁺ • 7H₂)

(H₃⁺ • 7) +  = (H₃⁺ • 8)

By formula: (H₃⁺ • 7H₂) + H₂ = (H₃⁺ • 8H₂)

(H₃⁺ • 8) +  = (H₃⁺ • 9)

By formula: (H₃⁺ • 8H₂) + H₂ = (H₃⁺ • 9H₂)

 +  = ( • )

By formula: H₃O⁺ + H₂ = (H₃O⁺ • H₂)

 +  = ( • )

By formula: K⁺ + H₂ = (K⁺ • H₂)

( • ) +  = ( • 2)

By formula: (K⁺ • H₂) + H₂ = (K⁺ • 2H₂)

 +  = ( • )

By formula: Li⁺ + H₂ = (Li⁺ • H₂)

 +  = ( • )

By formula: Na⁺ + H₂ = (Na⁺ • H₂)

( • ) +  = ( • 2)

By formula: (Na⁺ • H₂) + H₂ = (Na⁺ • 2H₂)

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Ion clustering data, 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]

Roder, Childs, et al., 1973
Roder, H.M.; Childs, G.E.; McCarty, R.D.; Angerhofer, P.E., Survey of the Prop. of the Hydrogen Isotopes Below Their Critical Temp, Natl. Bur. Stand. (U. S.), 1973. [all data]

Clusius and Weigand, 1940
Clusius, K.; Weigand, K., Melting Curves of the Gases A, Kr, Xe, CH4, CH3D, CD4, C2H4, C2H6, COS, and PH3 to 200 Atmospheres Pressure. The Chane of Volume on Melting, Z. Phys. Chem., Abt. B, 1940, 46, 1-37. [all data]

Henning and Otto, 1936
Henning, F.; Otto, J., Vapor pressure curves and triple points in the temperature region from 14 to 90 k, Phys. Z., 1936, 37, 633-8. [all data]

Onnes, Crommelin, et al., 1917
Onnes, H.K.; Crommelin, C.-A.; Cath, P.G., Isothermals of di-atomic substances and their binary mixtures. XIX. A preliminary determination of the critical point of hydrogen., Proc. K. Ned. Akad. Wet., 1917, 20, 178-184. [all data]

van Itterbeek, Verbeke, et al., 1964
van Itterbeek, A.; Verbeke, O.; Theewes, F.; Staes, K.; de Boelpaep, J., The Difference in Vapour Pressure Between Normal and Equilibrium Hydrogen. Vapour Pressure of Normal Hydrogen Between 20 ºK and 32 ºK, Physica (Amsterdam), 1964, 30, 6, 1238-1244, https://doi.org/10.1016/0031-8914(64)90114-4 . [all data]

Shul, Passarella, et al., 1987
Shul, R.J.; Passarella, R.; Upshulte, B.L.; Keesee, R.G.; Castleman, A.W., Thermal Energy Reactions Invoving Ar+ Monomer and Dimer with N2, H2, Xe, and Kr, J. Chem. Phys., 1987, 86, 8, 4446, https://doi.org/10.1063/1.452718 . [all data]

Dehmer and Pratt, 1982
Dehmer, P.M.; Pratt, S.T., Photoionization of ArKr, ArXe, and KrXe and bond dissociation energies of the rare gas dimer ions, J. Chem. Phys., 1982, 77, 4804. [all data]

Hiraoka and Kebarle, 1975
Hiraoka, K.; Kebarle, P., Stability and Structure of H3CO+ Formed from COH+ + H2 at Low Temperature, J. Chem. Phys., 1975, 63, 4, 1688, https://doi.org/10.1063/1.431499 . [all data]

Hiraoka, Kudaka, et al., 1991
Hiraoka, K.; Kudaka, I.; Yamabe, S., Gas-Phase Solvation of CH5+ with H2, Chem. Phys. Lett., 1991, 184, 4, 271, https://doi.org/10.1016/0009-2614(91)85122-D . [all data]

Hiraoka and Kebarle, 1976
Hiraoka, K.; Kebarle, P., Stabilities and Energetics of Pentacoordinated Carbonium Ions. The Isomeric C2H7+ Ions and Some Higher Analogues: C3H9+ and C4H11+, J. Am. Chem. Soc., 1976, 98, 20, 6119, https://doi.org/10.1021/ja00436a009 . [all data]

Kemper, Bushnell, et al., 1993
Kemper, P.R.; Bushnell, J.; Von Koppen, P.; Bowers, M.T., Binding Energies of Co+(H2/CH4/C2H6)1,2,3 Clusters, J. Phys. Chem., 1993, 97, 9, 1810, https://doi.org/10.1021/j100111a016 . [all data]

Kemper, Bushnell, et al., 1993, 2
Kemper, P.R.; Bushnell, J.; Von Helden, G.; Bowers, M.T., Co+(H2)n Clusters: Binding Energies and Molecular Parameters, J. Chem Phys., 1993, 97, 1, 52, https://doi.org/10.1021/j100103a012 . [all data]

Haynes and Armentrout, 1996
Haynes, C.L.; Armentrout, P.B., Guided Ion Beam Determination of the Co+ - H2 Bond Dissociation energy, Chem Phys. Let., 1996, 249, 1-2, 64, https://doi.org/10.1016/0009-2614(95)01337-7 . [all data]

Bushnell, Kemper, et al., 1995
Bushnell, J.E.; Kemper, P.R.; Bowers, M.T., Factors Affecting sigma Bond Activation in Simple Systems; Measurement of Experimental Binding energies of Fe+(H2)1-6 Clusters, J. Phys. Chem., 1995, 99, 42, 15602, https://doi.org/10.1021/j100042a040 . [all data]

Hiraoka, Saluja, et al., 1979
Hiraoka, K.; Saluja, P.P.S.; Kebarle, P., Stabilities of Complexes (N2)nH+, (CO)nH+ and (O2)nH+ for n = 1 to 7 Based on Gas Phase Ion Equilibrium Measurements, Can. J. Chem., 1979, 57, 16, 2159, https://doi.org/10.1139/v79-346 . [all data]

Paulson and Henchman, 1984
Paulson, J.F.; Henchman, M.J., NATO Advanced Study Institute, Ionic Processes in the Gas Phase, Series C, M. A. Almoster - Ferreira, ed(s)., Reidel, Boston, 1984, 331. [all data]

Hiraoka, 1987
Hiraoka, K., A Determination of the Stabilities of H3+(H2)n with n=1-9 from Measurements of the gas-Phase Ion Equilibria H3+(H2)n-1 + H2 = H3+(H2)n, J. Chem. Phys., 1987, 87, 7, 4048, https://doi.org/10.1063/1.452909 . [all data]

Beuhler, Ehrenson, et al., 1983
Beuhler, R.J.; Ehrenson, S.; Friedman, L., Hydrogen Cluster Ion Equilibria, J. Chem. Phys., 1983, 79, 12, 5982, https://doi.org/10.1063/1.445781 . [all data]

Hiraoka and Kebarle, 1975, 2
Hiraoka, K.; Kebarle, P., A Determination of the Stabilities of H5+, H7+, H9+, and H11+ from Measurement of the Gas Phase Ion Equilibria Hn+ + H2 = H(n + 2)+ (n = 3, 5, 7, 9), J. Chem. Phys., 1975, 62, 6, 2267, https://doi.org/10.1063/1.430751 . [all data]

Bennett and Field, 1972
Bennett, S.L.; Field, F.H., Reversible Reactions of Gaseous Ions. VII. The Hydrogen System, J. Am. Chem. Soc., 1972, 94, 25, 8669, https://doi.org/10.1021/ja00780a003 . [all data]

Okumura, Yeh, et al., 1990
Okumura, M.; Yeh, L.I.; Myers, J.D.; Lee, Y.T., Infrared Spectra of the Solvated Hydronium Ion: Vibrational Predissociation Spectroscopy of Mass-Selected H3O+.(H2O)n.(H2)m, J. Phys. Chem., 1990, 94, 9, 3416, https://doi.org/10.1021/j100372a014 . [all data]

Bushnell, Kemper, et al., 1994
Bushnell, J.E.; Kemper, P.R.; Bowers, M.T., Na+/K+(H2)1,2 clusters: experiment, J. Phys. Chem., 1994, 98, 8, 2044, https://doi.org/10.1021/j100059a011 . [all data]

Wu, 1979
Wu, C.H., Binding Energies of LiH2 and LiH2+ and the Ionization Potential of LiH2, J. Chem. Phys., 1979, 71, 2, 783, https://doi.org/10.1063/1.438367 . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Ion clustering data, References

• Symbols used in this document:
  

  Pc	Critical pressure
  Ptriple	Triple point pressure
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  T	Temperature
  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
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔrS°	Entropy of reaction at standard conditions
  ρc	Critical density

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