Hydrogen atom

Data at NIST subscription sites:

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, References, Notes

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

Quantity Value Units Method Reference Comment
Δfgas52.103 ± 0.001kcal/molReviewCox, Wagman, et al., 1984CODATA Review value
Δfgas52.103kcal/molReviewChase, 1998Data last reviewed in March, 1982
Quantity Value Units Method Reference Comment
gas,1 bar27.4180 ± 0.0005cal/mol*KReviewCox, Wagman, et al., 1984CODATA Review value
gas,1 bar27.419cal/mol*KReviewChase, 1998Data last reviewed in March, 1982

Gas Phase Heat Capacity (Shomate Equation)

Cp° = 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
    Cp = heat capacity (cal/mol*K)
    H° = standard enthalpy (kcal/mol)
    S° = standard entropy (cal/mol*K)
    t = temperature (K) / 1000.

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

View table.

Temperature (K) 298. to 6000.
A 4.967981
B 1.159331×10-10
C -3.783261×10-11
D 3.645079×10-12
E 7.639451×10-12
F 50.62189
G 33.43000
H 52.10311
ReferenceChase, 1998
Comment Data last reviewed in March, 1982

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:
MS - José A. Martinho Simões
B - John E. Bartmess

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

Hydromanganese pentacarbonyl (solution) = Hydrogen atom (solution) + C5MnO5 (solution)

By formula: C5HMnO5 (solution) = H (solution) + C5MnO5 (solution)

Quantity Value Units Method Reference Comment
Δr68.0 ± 1.0kcal/molEChemParker, Handoo, et al., 1991solvent: Acetonitrile; Please also see Tilset and Parker, 1989. The reaction enthalpy was obtained from the pKa of the hydride complex (MH), 14.1, and from the oxidation potential of the anion (M-), Mn(CO)5(-), by using the equation: ΔHrxn [kJ/mol] = 5.71pKa(MH) + 96.485(Eo)ox(M-) + C. C is a constant that was calculated as 59.49 kcal/mol Parker, Handoo, et al., 1991, by adjusting the previous equation to the calorimetrically derived values for the reactions Cr(Cp)(CO)3(H)(solution) = Cr(Cp)(CO)3(solution) + H(solution), 61.5 ± 1.0 kcal/mol, and Cr(Cp)(CO)2(PPh3)(H)(solution) = Cr(Cp)(CO)2(PPh3)(solution) + H(solution), 59.8 ± 1.0 kcal/mol Kiss, Zhang, et al., 1990. C depends on the solvent and on the reference electrode. The value given implies that the electrode potentials are referenced to ferrocene/ferricinium electrode; MS
Δr64.46kcal/molKinSBillmers, Griffith, et al., 1986solvent: Benzene; Please also see Sweany, Butler S.C., et al., 1981. The reaction enthalpy was derived according to the following procedure: the activation energy for the reaction 9,10-Me2C14H8(solution) + 2Mn(CO)5(H)(solution) = 9,10-Me2C14H10(solution) + Mn2(CO)10(solution), 21.7 kcal/mol, was reported in Sweany, Butler S.C., et al., 1981. The rate-limiting step of this reaction is the abstraction of hydrogen from Mn(CO)5(H), producing Mn(CO)5 and 9,10-Me2C14H9 radicals. Therefore, the activation energy is approximately equal to the difference between the enthalpies of the reactions Mn(CO)5(H)(solution) = Mn(CO)5(solution) + H(solution) and 9,10-Me2C14H9(solution) = 9,10-Me2C14H8(solution). The latter was taken as 42.76 kcal/mol Billmers, Griffith, et al., 1986; MS

C7H6FeO2 (solution) = C7H5FeO2 (solution) + Hydrogen atom (solution)

By formula: C7H6FeO2 (solution) = C7H5FeO2 (solution) + H (solution)

Quantity Value Units Method Reference Comment
Δr57.1 ± 1.0kcal/molEChemParker, Handoo, et al., 1991solvent: Acetonitrile; Please also see Tilset and Parker, 1989. The reaction enthalpy was obtained from the pKa of the hydride complex (MH), 19.4, and from the oxidation potential of the anion (M-), Fe(Cp)(CO)2(-), by using the equation: ΔHrxn [kJ/mol] = 5.71pKa(MH) + 96.485(Eo)ox(M-) + C. C is a constant that was calculated as 59.49 kcal/mol Parker, Handoo, et al., 1991, by adjusting the previous equation to the calorimetrically derived values for the reactions Cr(Cp)(CO)3(H)(solution) = Cr(Cp)(CO)3(solution) + H(solution), 61.5 ± 1.0 kcal/mol, and Cr(Cp)(CO)2(PPh3)(H)(solution) = Cr(Cp)(CO)2(PPh3)(solution) + H(solution), 59.8 ± 1.0 kcal/mol Kiss, Zhang, et al., 1990. C depends on the solvent and on the reference electrode. The value given implies that the electrode potentials are referenced to ferrocene/ferricinium electrode; MS

C5HO5Re (solution) = Hydrogen atom (solution) + C5O5Re (solution)

By formula: C5HO5Re (solution) = H (solution) + C5O5Re (solution)

Quantity Value Units Method Reference Comment
Δr74.7 ± 1.0kcal/molEChemParker, Handoo, et al., 1991solvent: Acetonitrile; Please also see Tilset and Parker, 1989. The reaction enthalpy was obtained from the pKa of the hydride complex (MH), 21.1, and from the oxidation potential of the anion (M-), Re(CO)5(-), by using the equation: ΔHrxn [kJ/mol] = 5.71pKa(MH) + 96.485(Eo)ox(M-) + C. C is a constant that was calculated as 59.49 kcal/mol Parker, Handoo, et al., 1991, by adjusting the previous equation to the calorimetrically derived values for the reactions Cr(Cp)(CO)3(H)(solution) = Cr(Cp)(CO)3(solution) + H(solution), 61.5 ± 1.0 kcal/mol, and Cr(Cp)(CO)2(PPh3)(H)(solution) = Cr(Cp)(CO)2(PPh3)(solution) + H(solution), 59.8 ± 1.0 kcal/mol Kiss, Zhang, et al., 1990. C depends on the solvent and on the reference electrode. The value given implies that the electrode potentials are referenced to ferrocene/ferricinium electrode; MS

Cobalt, tetracarbonylhydro- (solution) = Hydrogen atom (solution) + Cobalt, tetracarbonyl (solution)

By formula: C4HCoO4 (solution) = H (solution) + C4CoO4 (solution)

Quantity Value Units Method Reference Comment
Δr66.4 ± 1.0kcal/molEChemParker, Handoo, et al., 1991solvent: Acetonitrile; Please also see Tilset and Parker, 1989. The reaction enthalpy was obtained from the pKa of the hydride complex (MH), 8.3, and from the oxidation potential of the anion (M-), Co(CO)4(-), by using the equation: ΔHrxn [kJ/mol] = 5.71pKa(MH) + 96.485(Eo)ox(M-) + C. C is a constant that was calculated as 59.49 kcal/mol Parker, Handoo, et al., 1991, by adjusting the previous equation to the calorimetrically derived values for the reactions Cr(Cp)(CO)3(H)(solution) = Cr(Cp)(CO)3(solution) + H(solution), 61.5 ± 1.0 kcal/mol, and Cr(Cp)(CO)2(PPh3)(H)(solution) = Cr(Cp)(CO)2(PPh3)(solution) + H(solution), 59.8 ± 1.0 kcal/mol Kiss, Zhang, et al., 1990. C depends on the solvent and on the reference electrode. The value given implies that the electrode potentials are referenced to ferrocene/ferricinium electrode; MS

C4H2FeO4 (g) = 2Hydrogen atom (g) + C4FeO4 (g)

By formula: C4H2FeO4 (g) = 2H (g) + C4FeO4 (g)

Quantity Value Units Method Reference Comment
Δr130.kcal/molESTMiller and Beauchamp, 1991Please also see Martinho Simões and Beauchamp, 1990. The reaction enthalpy was estimated from the activation enthalpy for thermal decomposition in solution, 26. ± 2. kcal/mol Pearson and Mauermann, 1982, yielding Fe(CO)4 and H2, and from the activation enthalpy of the oxidative addition of H2 to Fe(CO)4 in a rare gas matrix, ca. 0. kcal/mol Sweany, 1981, yielding Fe(CO)4H2. The enthalpy of formation relies on -105.1 ± 3.4 kcal/mol for the enthalpy of formation of Fe(CO)4(g); MS

Hydromanganese pentacarbonyl (g) = Hydrogen atom (g) + C5MnO5 (g)

By formula: C5HMnO5 (g) = H (g) + C5MnO5 (g)

Quantity Value Units Method Reference Comment
Δr58.6 ± 4.1kcal/molPIMSMartinho Simões and Beauchamp, 1990The reaction enthalpy was derived from the appearance energy of Mn(CO)5(+), 237.5 ± 2.3 kcal/mol, using Mn(CO)5(H) as the neutral precursor, together with the adiabatic ionization energy of Mn(CO)5 radical, 179. ± 3.3 kcal/mol Martinho Simões and Beauchamp, 1990; MS

C3H10Ge (g) = C3H9Ge (g) + Hydrogen atom (g)

By formula: C3H10Ge (g) = C3H9Ge (g) + H (g)

Quantity Value Units Method Reference Comment
Δr79.8 ± 2.9kcal/molICRBrinkman, Salomon, et al., 1995The reaction enthalpy was derived from the acidity of Ge(Me)3(H)(g), 361.5 ± 2.8 kcal/mol, the electron affinity of Ge(Me)3(g), 31.91 ± 0.69 kcal/mol Brinkman, Salomon, et al., 1995, and the ionization energy of H(g), 313.58 kcal/mol Lias, Bartmess, et al., 1988.; MS

C3H10Sn (g) = Hydrogen atom (g) + Trimethyltin (g)

By formula: C3H10Sn (g) = H (g) + C3H9Sn (g)

Quantity Value Units Method Reference Comment
Δr74.6 ± 2.5kcal/molICRBrinkman, Salomon, et al., 1995The reaction enthalpy was derived from the acidity of Sn(Me)3(H)(g), 349.0 ± 2.0 kcal/mol, the electron affinity of Sn(Me)3(g), 39.2 ± 1.5 kcal/mol Brinkman, Salomon, et al., 1995, and the ionization energy of H(g), 313.58 kcal/mol Lias, Bartmess, et al., 1988.; MS

Germane (g) = Hydrogen atom (g) + Germyl radical (g)

By formula: H4Ge (g) = H (g) + H3Ge (g)

Quantity Value Units Method Reference Comment
Δr83.4 ± 2.0kcal/molPIMSBerkowitz, Ellison, et al., 1994Please also see Ruscic, Schwarz, et al., 1990. Value recommended in the critical survey Berkowitz, Ellison, et al., 1994.; MS
Δr<85.6kcal/molPIMSRuscic, Schwarz, et al., 1990Temperature: 0 K. A value of 82. ± 2. kcal/mol is recommended in Ruscic, Schwarz, et al., 1990.; MS

e- + Hydrogen cation = Hydrogen atom

By formula: e- + H+ = H

Quantity Value Units Method Reference Comment
Δr315.10kcal/molAcidWagman, Evans, et al., 1982gas phase; Using the "electron convention". Acid = H.; B
Quantity Value Units Method Reference Comment
Δr314.00kcal/molH-TSWagman, Evans, et al., 1982gas phase; Using the "electron convention". Acid = H.; B

Germyl radical (g) = Hydrogen atom (g) + Germylene (g)

By formula: H3Ge (g) = H (g) + H2Ge (g)

Quantity Value Units Method Reference Comment
Δr>56.4kcal/molPIMSRuscic, Schwarz, et al., 1990Temperature: 0 K. A value of 59.0 kcal/mol is recommended in Ruscic, Schwarz, et al., 1990.; MS

Germylene (g) = HGe (g) + Hydrogen atom (g)

By formula: H2Ge (g) = HGe (g) + H (g)

Quantity Value Units Method Reference Comment
Δr<68.8kcal/molPIMSRuscic, Schwarz, et al., 1990Temperature: 0 K. A value of 66.2 kcal/mol is recommended in Ruscic, Schwarz, et al., 1990.; MS

HGe (g) = Hydrogen atom (g) + germanium (g)

By formula: HGe (g) = H (g) + Ge (g)

Quantity Value Units Method Reference Comment
Δr>53.8kcal/molPIMSRuscic, Schwarz, et al., 1990Temperature: 0 K. A value of 63.1 kcal/mol is recommended in Ruscic, Schwarz, et al., 1990.; MS

H3Sb (g) = Hydrogen atom (g) + H2Sb (g)

By formula: H3Sb (g) = H (g) + H2Sb (g)

Quantity Value Units Method Reference Comment
Δr68.91 ± 0.50kcal/molPIMSBerkowitz, Ellison, et al., 1994Value recommended in the critical survey Berkowitz, Ellison, et al., 1994.; MS

C13H26IrP (solution) = C13H24IrP (solution) + 2Hydrogen atom (g)

By formula: C13H26IrP (solution) = C13H24IrP (solution) + 2H (g)

Quantity Value Units Method Reference Comment
Δr148.kcal/molESTNolan, Hoff, et al., 1987Please also see Stoutland, Bergman, et al., 1988.; MS

(CAS Reg. No. 952499-85-3 • 4294967295Hydrogen atom) + Hydrogen atom = CAS Reg. No. 952499-85-3

By formula: (CAS Reg. No. 952499-85-3 • 4294967295H) + H = CAS Reg. No. 952499-85-3

Quantity Value Units Method Reference Comment
Δr44.7 ± 4.2kcal/molN/ACalvi, Andrews, et al., 2007gas phase; B

C13H26IrP (solution) = C13H25IrP (solution) + Hydrogen atom (g)

By formula: C13H26IrP (solution) = C13H25IrP (solution) + H (g)

Quantity Value Units Method Reference Comment
Δr72.9 ± 4.3kcal/molPACNolan, Hoff, et al., 1987MS

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.

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]

Parker, Handoo, et al., 1991
Parker, V.D.; Handoo, K.L.; Roness, F.; Tilset, M., J. Am. Chem. Soc., 1991, 113, 7493. [all data]

Tilset and Parker, 1989
Tilset, M.; Parker, V.D., J. Am. Chem. Soc., 1989, 111, 6711; ibid. 1990. [all data]

Kiss, Zhang, et al., 1990
Kiss, G.; Zhang, K.; Mukerjee, S.L.; Hoff, C.; Roper, G.C., J. Am. Chem. Soc., 1990, 112, 5657. [all data]

Billmers, Griffith, et al., 1986
Billmers, R.; Griffith, L.L.; Stein, S.E., J. Phys. Chem., 1986, 90, 517. [all data]

Sweany, Butler S.C., et al., 1981
Sweany, R.; Butler S.C.; Halpern, J., J. Organometal. Chem., 1981, 213, 487. [all data]

Miller and Beauchamp, 1991
Miller, A.E.S.; Beauchamp, J.L., J. Am. Chem. Soc., 1991, 113, 8765. [all data]

Martinho Simões and Beauchamp, 1990
Martinho Simões, J.A.; Beauchamp, J.L., Chem. Rev., 1990, 90, 629. [all data]

Pearson and Mauermann, 1982
Pearson, R.G.; Mauermann, H., J. Am. Chem. Soc., 1982, 104, 500. [all data]

Sweany, 1981
Sweany, R.L., J. Am. Chem. Soc., 1981, 103, 2410. [all data]

Brinkman, Salomon, et al., 1995
Brinkman, E.A.; Salomon, K.; Tumas, W.; Brauman, J.I., Electron affinities and gas-phase acidities of organogermanium and organotin compounds, J. Am. Chem. Soc., 1995, 117, 17, 4905, https://doi.org/10.1021/ja00122a022 . [all data]

Lias, Bartmess, et al., 1988
Lias, S.G.; Bartmess, J.E.; Liebman, J.F.; Holmes, J.L.; Levin, R.D.; Mallard, W.G., Gas-Phase Ion and Neutral Thermochemistry, J. Phys. Chem. Ref. Data, 1988, 17, Suppl. 1. [all data]

Berkowitz, Ellison, et al., 1994
Berkowitz, J.; Ellison, G.B.; Gutman, D., Three methods to measure RH bond energies, J. Phys. Chem., 1994, 98, 2744. [all data]

Ruscic, Schwarz, et al., 1990
Ruscic, B.; Schwarz, M.; Berkowitz, J., Photoionization studies of GeHn(n = 2-4), J. Chem. Phys., 1990, 92, 1865. [all data]

Wagman, Evans, et al., 1982
Wagman, D.D.; Evans, W.H.; Parker, V.B.; Schumm, R.H.; Halow, I.; Bailey, S.M.; Churney, K.L.; Nuttall, R.L., The NBS Tables of Chemical Thermodynamic Properties (NBS Tech Note 270), J. Phys. Chem. Ref. Data, Supl. 1, 1982, 11. [all data]

Nolan, Hoff, et al., 1987
Nolan, S.P.; Hoff, C.D.; Stoutland, P.O.; Newman, L.J.; Buchanan, J.M.; Bergman, R.G.; Yang, G.K.; Peters, K.S., J. Am. Chem. Soc., 1987, 109, 3143. [all data]

Stoutland, Bergman, et al., 1988
Stoutland, P.O.; Bergman, R.G.; Nolan, S.P.; Hoff, C.D., Polyhedron, 1988, 7, 1429. [all data]

Calvi, Andrews, et al., 2007
Calvi, R.M.D.; Andrews, D.H.; Lineberger, W.C., Negative ion photoelectron spectroscopy of copper hydrides, Chem. Phys. Lett., 2007, 442, 1-3, 12-16, https://doi.org/10.1016/j.cplett.2007.05.060 . [all data]


Notes

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