Hydrogen

Formula: H₂
Molecular weight: 2.01588
IUPAC Standard InChI: InChI=1S/H2/h1H
IUPAC Standard InChIKey: UFHFLCQGNIYNRP-UHFFFAOYSA-N
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
The 3d structure may be viewed using Java or Javascript.
Isotopologues:
Other names: Dihydrogen; o-Hydrogen; p-Hydrogen; Molecular hydrogen; H2; UN 1049; UN 1966
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Information on this page:
Other data available:
- Reaction thermochemistry data: 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
- Constants of diatomic molecules
- Fluid Properties
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Gas phase thermochemistry data

Go To: Top, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), References, Notes

Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	130.680 ± 0.003	J/mol*K	Review	Cox, Wagman, et al., 1984	CODATA Review value
S°_{gas,1 bar}	130.68	J/mol*K	Review	Chase, 1998	Data last reviewed in March, 1977

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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View table.

Temperature (K)	298. to 1000.	1000. to 2500.	2500. to 6000.
A	33.066178	18.563083	43.413560
B	-11.363417	12.257357	-4.293079
C	11.432816	-2.859786	1.272428
D	-2.772874	0.268238	-0.096876
E	-0.158558	1.977990	-20.533862
F	-9.980797	-1.147438	-38.515158
G	172.707974	156.288133	162.081354
H	0.0	0.0	0.0
Reference	Chase, 1998	Chase, 1998	Chase, 1998
Comment	Data last reviewed in March, 1977; New parameter fit October 2001	Data last reviewed in March, 1977; New parameter fit October 2001	Data last reviewed in March, 1977; New parameter fit October 2001

Phase change data

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), References, Notes

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director

Quantity	Value	Units	Method	Reference	Comment
T_triple	0.	K	N/A	Roder, Childs, et al., 1973	TRC
T_triple	13.95	K	N/A	Clusius and Weigand, 1940	Uncertainty assigned by TRC = 0.06 K; see property X for dP/dT for c-l equil.; TRC
T_triple	13.96	K	N/A	Henning and Otto, 1936	Uncertainty assigned by TRC = 0.05 K; temperature measured with He gas thermometer; TRC
Quantity	Value	Units	Method	Reference	Comment
P_triple	0.	bar	N/A	Roder, Childs, et al., 1973	TRC
P_triple	0.0721	bar	N/A	Henning and Otto, 1936	Uncertainty assigned by TRC = 0.0004 bar; TRC
Quantity	Value	Units	Method	Reference	Comment
T_c	33.18	K	N/A	Onnes, Crommelin, et al., 1917	Uncertainty assigned by TRC = 0.2 K; derived from P-V-T measurements; TRC
Quantity	Value	Units	Method	Reference	Comment
P_c	13.00	bar	N/A	Onnes, Crommelin, et al., 1917	Uncertainty assigned by TRC = 0.0119 bar; derived from vapor pressure extrapolated to Tc; TRC
Quantity	Value	Units	Method	Reference	Comment
ρ_c	15.4	mol/l	N/A	Onnes, Crommelin, et al., 1917	Uncertainty assigned by TRC = 2. mol/l; by extrapolation of rectilinear diameter to Tc; TRC

Antoine Equation Parameters

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

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Temperature (K)	A	B	C	Reference	Comment
21.01 to 32.27	3.54314	99.395	7.726	van Itterbeek, Verbeke, et al., 1964	Coefficents calculated by NIST from author's data.

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), References, Notes

Data compiled as indicated in comments:
MS - José A. Martinho Simões
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
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.

Reactions 1 to 50

(solution) + Hydrogen (solution) = 2 (solution)

By formula: C₈Co₂O₈ (solution) + H₂ (solution) = 2C₄HCoO₄ (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	19.7 ± 0.8	kJ/mol	EqS	Rathke, Klingler, et al., 1992	solvent: Supercritical carbon dioxide; Temperature range: 333-453 K. The results corrected for 1 atm pressure of H2 are 16.7 kJ/mol and -17.6 J/(mol K) Rathke, Klingler, et al., 1992; MS
Δ_rH°	13.0 ± 0.9	kJ/mol	EqS	Bor, 1986	solvent: n-Hexane; Temperature range: ca. 300-420 K; MS
Δ_rH°	26.4	kJ/mol	KinS	Alemdaroglu, Penninger, et al., 1976	solvent: n-Heptane; The reaction enthalpy relies on the experimental values for the forward and reverse activation enthalpies, 72.4 and 46.0 kJ/mol, respectively Alemdaroglu, Penninger, et al., 1976. A rather different value has, however, been reported for the activation enthalpy of the forward reaction, 104.6 kJ/mol Ungváry, 1972; MS
Δ_rH°	27.6	kJ/mol	EqS	Alemdaroglu, Penninger, et al., 1976	solvent: n-Heptane; Temperature range: 353-428 K; MS
Δ_rH°	13.4	kJ/mol	EqS	Ungváry, 1972	solvent: n-Heptane; Temperature range: 307-428 K. The results corrected for 1 atm pressure of H2 are 18.0 kJ/mol and -10.9 J/(mol K) Rathke, Klingler, et al., 1992; MS

H₃⁺ + Hydrogen = (H₃⁺ • )

By formula: H₃⁺ + H₂ = (H₃⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	29. ± 2.	kJ/mol	AVG	N/A	Average of 4 out of 11 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	72.8 to 72.8	J/mol*K	RNG	N/A	Range of 6 values; Individual data points

C₁₁H₂O₁₁Os (solution) + (solution) = Hydrogen (g) + (solution)

By formula: C₁₁H₂O₁₁Os (solution) + CO (solution) = H₂ (g) + C₁₂O₁₂Os₃ (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-37.7 ± 9.6	kJ/mol	ES/KS	Poë, Sampson, et al., 1993	solvent: Decalin; Calculated from equilibrium and kinetic data Poë, Sampson, et al., 1993.; MS
Δ_rH°	-77.4 ± 9.7	kJ/mol	N/A	Poë, Sampson, et al., 1993	solvent: Decalin; Calculated from data for the reactions Os3(CO)10(H)2(solution) + CO(solution) = Os3(CO)11(H)2(solution) (hrxn [kJ/mol]=-39.7±1.3, srxn [J/(mol K)]=-80.3±3.8) and Os3(CO)11(H)2(solution) + CO(solution) = Os3(CO)12(solution) + H2(g) (hrxn [kJ/mol]=-37.7±9.6, srxn [J/(mol K)]=-32.6±27.6) Poë, Sampson, et al., 1993.; MS

+ Hydrogen =

By formula: C₆H₁₀ + H₂ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-118. ± 6.	kJ/mol	AVG	N/A	Average of 8 values; Individual data points

(cr) + Hydrogen (g) = 2C₈H₆CrO₃ (cr)

By formula: C₁₆H₁₀Cr₂O₆ (cr) + H₂ (g) = 2C₈H₆CrO₃ (cr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-13.9 ± 4.0	kJ/mol	RSC	Landrum and Hoff, 1985	The reaction enthalpy was obtained from the value for the reaction 2Cr(Cp)(CO)3(H)(cr) + 1,3-cy-C6H8(solution) = [Cr(Cp)(CO)3]2(cr) + cy-C6H10(solution), -98.3 ± 3.8 kJ/mol Landrum and Hoff, 1985, together with the calculated enthalpy for 1,3-cy-C6H8(l) + H2(g) = cy-C6H10(l), -112.2±1.3 Pedley, 1994. It was assumed that 1,3-cy-C6H8 and cy-C6H10 have similar solution enthalpies in heptane; MS
Δ_rH°	-15.1 ± 4.2	kJ/mol	DSC	Landrum and Hoff, 1985	The reaction enthalpy was obtained from the value for the reaction 2Cr(Cp)(CO)3(H)(cr) + 1,3-cy-C6H8(solution) = [Cr(Cp)(CO)3]2(cr) + cy-C6H10(solution), -98.3 ± 3.8 kJ/mol Landrum and Hoff, 1985, together with the calculated enthalpy for 1,3-cy-C6H8(l) + H2(g) = cy-C6H10(l), -112.2±1.3 Pedley, 1994. It was assumed that 1,3-cy-C6H8 and cy-C6H10 have similar solution enthalpies in heptane; MS

Hydrogen + =

By formula: H₂ + C₆H₁₂ = C₆H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-125. ± 3.	kJ/mol	AVG	N/A	Average of 8 values; Individual data points

(H₃⁺ • Hydrogen ) + = (H₃⁺ • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14. ± 0.8	kJ/mol	PHPMS	Hiraoka, 1987	gas phase; M
Δ_rH°	13.	kJ/mol	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase; M
Δ_rH°	14.	kJ/mol	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase; deuterated; M
Δ_rH°	17.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rH°	7.5	kJ/mol	HPMS	Bennett and Field, 1972	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	72.8	J/mol*K	PHPMS	Hiraoka, 1987	gas phase; M
Δ_rS°	70.7	J/mol*K	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase; M
Δ_rS°	67.4	J/mol*K	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase; deuterated; M
Δ_rS°	82.8	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rS°	45.2	J/mol*K	HPMS	Bennett and Field, 1972	gas phase; Entropy change is questionable; M

Hydrogen + =

By formula: H₂ + C₇H₁₄ = C₇H₁₆

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-125. ± 2.	kJ/mol	AVG	N/A	Average of 6 values; Individual data points

+ Hydrogen =

By formula: C₈H₁₆ + H₂ = C₈H₁₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-125. ± 6.	kJ/mol	AVG	N/A	Average of 7 values; Individual data points

+ = Hydrogen

By formula: H^- + H⁺ = H₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1675.3	kJ/mol	N/A	Shiell, Hu, et al., 2000	gas phase; Given: 139714.8±1 cm-1 at 0K, or 399.465±0.003 kcal/mol; B
Δ_rH°	1675.3	kJ/mol	N/A	Pratt, McCormack, et al., 1992	gas phase; 399.46±0.01 kcal/mol at 0K; 0.94 correction, Gurvich, Veyts, et al.; B
Δ_rH°	1675.3	kJ/mol	D-EA	Lykke, Murray, et al., 1991	gas phase; Reported: 6082.99±0.15 cm-1, or 0.754195(18) eV; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1649.3 ± 0.42	kJ/mol	H-TS	Shiell, Hu, et al., 2000	gas phase; Given: 139714.8±1 cm-1 at 0K, or 399.465±0.003 kcal/mol; B
Δ_rG°	1649.3	kJ/mol	H-TS	Lykke, Murray, et al., 1991	gas phase; Reported: 6082.99±0.15 cm-1, or 0.754195(18) eV; B

Hydrogen + =

By formula: H₂ + C₅H₈ = C₅H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-112.7 ± 0.54	kJ/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane; ALS
Δ_rH°	-112. ± 0.8	kJ/mol	Chyd	Roth and Lennartz, 1980	liquid phase; solvent: Cyclohexane; ALS
Δ_rH°	-109.0 ± 1.8	kJ/mol	Chyd	Turner, Jarrett, et al., 1973	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-110. ± 0.8	kJ/mol	Chyd	Rogers and McLafferty, 1971	liquid phase; solvent: Hydrocarbon; ALS
Δ_rH°	-111.6 ± 0.3	kJ/mol	Chyd	Dolliver, Gresham, et al., 1937	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -112.6 ± 0.3 kJ/mol; At 355 °K; ALS

Hydrogen + =

By formula: H₂ + C₈H₁₄ = C₈H₁₆

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-102.	kJ/mol	Chyd	Doering, Roth, et al., 1989	liquid phase; ALS
Δ_rH°	-103. ± 0.8	kJ/mol	Chyd	Roth and Lennartz, 1980	liquid phase; solvent: Cyclohexane; ALS
Δ_rH°	-96.40 ± 0.71	kJ/mol	Chyd	Rogers, Von Voithenberg, et al., 1978	liquid phase; solvent: Hexane; ALS
Δ_rH°	-96.1 ± 0.4	kJ/mol	Chyd	Turner and Meador, 1957	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-97.40 ± 0.63	kJ/mol	Chyd	Conn, Kistiakowsky, et al., 1939	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -98.4 ± 0.2 kJ/mol; At 355 K; ALS

0.5C₃₆H₈₄Cl₂P₄Rh₂ (solution) + Hydrogen (g) = C₁₈H₄₄ClP₂Rh (solution)

By formula: 0.5C₃₆H₈₄Cl₂P₄Rh₂ (solution) + H₂ (g) = C₁₈H₄₄ClP₂Rh (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-98.8 ± 2.7	kJ/mol	RSC	Wang, Rosini, et al., 1995	solvent: Benzene; The reaction enthalpy was calculated from the enthalpies of the reactions Rh[P(i-Pr)3]2(Cl)(H)2(solution) + t-BuNC(solution) = Rh[P(i-Pr)3]2(Cl)(CN-t-Bu)(solution) + H2(g), -41.4 ± 1.7 kJ/mol, and 0.5{Rh[P(i-Pr)3]2(Cl)}2(solution) + t-BuNC(solution) = Rh[P(i-Pr)3]2(Cl)(CN-t-Bu)(solution), -140.2 ± 2.1 kJ/mol Wang, Rosini, et al., 1995. The enthalpy of solution of {Rh[P(i-Pr)3]2(Cl)}2(cr) was measured as 20.1 ± 1.3 kJ/mol Wang, Rosini, et al., 1995.; MS

Hydrogen + =

By formula: H₂ + C₆H₁₀ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-100.8 ± 0.63	kJ/mol	Chyd	Rogers, Crooks, et al., 1987	liquid phase; ALS
Δ_rH°	-101.3 ± 0.50	kJ/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane; ALS
Δ_rH°	-96.3 ± 0.2	kJ/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-96.3 ± 0.2	kJ/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-96.3 ± 0.2	kJ/mol	Chyd	Turner and Garner, 1957, 2	liquid phase; solvent: Acetic acid; ALS

2 Hydrogen + =

By formula: 2H₂ + C₆H₁₀ = C₆H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-252. ± 2.	kJ/mol	Chyd	Fang and Rogers, 1992	liquid phase; solvent: Cyclohexane; ALS
Δ_rH°	-253.9 ± 2.7	kJ/mol	Chyd	Molnar, Rachford, et al., 1984	liquid phase; solvent: Dioxane; ALS
Δ_rH°	-251.8 ± 1.5	kJ/mol	Chyd	Turner, Mallon, et al., 1973	liquid phase; solvent: Glacial acetic acid; ALS
Δ_rH°	-251.2 ± 0.42	kJ/mol	Chyd	Kistiakowsky, Ruhoff, et al., 1936	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -253.3 ± 0.63 kJ/mol; At 355 °K; ALS

Hydrogen + =

By formula: H₂ + C₇H₁₂ = C₇H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-101.9 ± 0.63	kJ/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane; ALS
Δ_rH°	-98.3 ± 0.8	kJ/mol	Chyd	Rogers and McLafferty, 1971	liquid phase; solvent: Hydrocarbon; ALS
Δ_rH°	-98.58 ± 0.46	kJ/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-98.58 ± 0.46	kJ/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid; ALS

Hydrogen + =

By formula: H₂ + C₇H₁₂ = C₇H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-106.9 ± 0.4	kJ/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane; ALS
Δ_rH°	-101. ± 0.8	kJ/mol	Chyd	Rogers and McLafferty, 1971	liquid phase; solvent: Hydrocarbon; ALS
Δ_rH°	-104.1 ± 0.50	kJ/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-104.1 ± 0.50	kJ/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid; ALS

Hydrogen + =

By formula: H₂ + C₆H₁₀ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-115.9 ± 0.96	kJ/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane; ALS
Δ_rH°	-112.5 ± 0.08	kJ/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-112.3 ± 0.2	kJ/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-112.2 ± 0.3	kJ/mol	Chyd	Turner and Garner, 1957, 2	liquid phase; solvent: Acetic acid; ALS

C₃H₇⁺ + Hydrogen = (C₃H₇⁺ • )

By formula: C₃H₇⁺ + H₂ = (C₃H₇⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1976	gas phase; Entropy change calculated or estimated, DG<, Δ_rH<; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Hiraoka and Kebarle, 1976	gas phase; Entropy change calculated or estimated, DG<, Δ_rH<; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
4.	170.	PHPMS	Hiraoka and Kebarle, 1976	gas phase; Entropy change calculated or estimated, DG<, Δ_rH<; M

+ Hydrogen = ( • )

By formula: Co⁺ + H₂ = (Co⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	82. ± 4.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(O K)=76.1 kJ/mol, Δ_rS(300 K)=86.2 J/mol*K; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.0	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(O K)=76.1 kJ/mol, Δ_rS(300 K)=86.2 J/mol*K; M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
73.2 (+9.6,-0.)		CID	Haynes and Armentrout, 1996	gas phase; guided ion beam CID; M

+ Hydrogen =

By formula: C₅H₁₀ + H₂ = C₅H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-126.6 ± 2.4	kJ/mol	Chyd	Molnar, Rachford, et al., 1984	liquid phase; solvent: Dioxane; ALS
Δ_rH°	-125.0 ± 1.8	kJ/mol	Chyd	Molnar, Rachford, et al., 1984	liquid phase; solvent: Hexane; ALS
Δ_rH°	-122.6 ± 2.4	kJ/mol	Chyd	Rogers and Skanupong, 1974	liquid phase; solvent: Hexane; ALS
Δ_rH°	-119. ± 1.	kJ/mol	Chyd	Rogers and McLafferty, 1971	liquid phase; solvent: Hydrocarbon; ALS

+ Hydrogen =

By formula: C₇H₁₂ + H₂ = C₇H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-119.5 ± 0.65	kJ/mol	Chyd	Rogers, Crooks, et al., 1987	liquid phase; ALS
Δ_rH°	-116.1 ± 0.54	kJ/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-116.1 ± 0.54	kJ/mol	Eqk	Turner and Garner, 1957	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-120.1 ± 0.3	kJ/mol	Chyd	Turner and Garner, 1957, 2	liquid phase; solvent: Acetic acid; ALS

Hydrogen + =

By formula: H₂ + C₇H₁₂ = C₇H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-110. ± 0.4	kJ/mol	Chyd	Roth and Lennartz, 1980	liquid phase; solvent: Cyclohexane; ALS
Δ_rH°	-108.2 ± 0.4	kJ/mol	Chyd	Turner, Meador, et al., 1957	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-108.9 ± 0.63	kJ/mol	Chyd	Conn, Kistiakowsky, et al., 1939	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -111.0 ± 0.08 kJ/mol; At 355 K; ALS

3 Hydrogen + =

By formula: 3H₂ + C₇H₈ = C₇H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-305. ± 0.4	kJ/mol	Chyd	Roth, Klaerner, et al., 1983	liquid phase; solvent: Isooctane; ALS
Δ_rH°	-294.9 ± 1.6	kJ/mol	Chyd	Turner, Meador, et al., 1957	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-301.7 ± 1.3	kJ/mol	Chyd	Conn, Kistiakowsky, et al., 1939	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -304.8 ± 0.04 kJ/mol; at 355 K; ALS

2 Hydrogen + =

By formula: 2H₂ + C₆H₁₀ = C₆H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-231.4 ± 3.0	kJ/mol	Chyd	Molnar, Rachford, et al., 1984	liquid phase; solvent: Dioxane; ALS
Δ_rH°	-227.0 ± 2.8	kJ/mol	Chyd	Molnar, Rachford, et al., 1984	liquid phase; solvent: Hexane; ALS
Δ_rH°	-223.4 ± 0.63	kJ/mol	Chyd	Dolliver, Gresham, et al., 1937	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -225.4 ± 0.63 kJ/mol; At 355 °K; ALS

+ 3 Hydrogen =

By formula: C₅H₅N + 3H₂ = C₅H₁₁N

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-193.8 ± 0.75	kJ/mol	Eqk	Hales and Herington, 1957	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -202.2 ± 0.75 kJ/mol; At 400-550 K; ALS
Δ_rH°	-193.0 ± 2.1	kJ/mol	Eqk	Burrows and King, 1935	liquid phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -188.3 kJ/mol; At 423-443 K; ALS

+ Hydrogen =

By formula: C₈H₁₆ + H₂ = C₈H₁₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-107.	kJ/mol	Chyd	Turner, Nettleton, et al., 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-112.9 ± 0.3	kJ/mol	Chyd	Dolliver, Gresham, et al., 1937	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -114.0 ± 0.3 kJ/mol; At 355 °K; ALS
Δ_rH°	-119.6 ± 3.3	kJ/mol	Chyd	Crawford and Parks, 1936	liquid phase; ALS

+ Hydrogen =

By formula: C₃H₆ + H₂ = C₃H₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-123.4 ± 5.0	kJ/mol	Chyd	Kistiakowsky and Nickle, 1951	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -124.9 ± 2.1 kJ/mol; ALS
Δ_rH°	-125.0 ± 0.42	kJ/mol	Chyd	Kistiakowsky, Ruhoff, et al., 1935	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -126.00 ± 0.054 kJ/mol; At 355 °K; ALS

( • ) + Hydrogen = ( • • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	95.8	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; switching reaction(Co+).2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993; M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
73. (+3.,-0.)		SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; switching reaction(Co+).2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993; M

Hydrogen + =

By formula: H₂ + C₃H₆O = C₃H₈O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-68.74 ± 0.42	kJ/mol	Cm	Wiberg, Crocker, et al., 1991	liquid phase; ALS
Δ_rH°	-55.23	kJ/mol	Eqk	Buckley and Herington, 1965	gas phase; ALS
Δ_rH°	-55.40 ± 0.42	kJ/mol	Chyd	Dolliver, Gresham, et al., 1938	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -56.1 ± 0.4 kJ/mol; At 355 °K; ALS

( • Hydrogen ) + = ( • • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	91.2	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; switching reaction(Co+)2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993; M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
94.6 (+5.0,-0.)		SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; switching reaction(Co+)2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993; M

+ Hydrogen =

By formula: C₈H₁₄ + H₂ = C₈H₁₆

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-110. ± 1.	kJ/mol	Chyd	Rogers and McLafferty, 1971	liquid phase; solvent: Hydrocarbon; ALS
Δ_rH°	-110.1 ± 0.2	kJ/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-110.1 ± 0.2	kJ/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid; ALS

Hydrogen + =

By formula: H₂ + C₈H₁₄ = C₈H₁₆

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-144. ± 0.4	kJ/mol	Chyd	Roth, Adamczak, et al., 1991	liquid phase; see Doering, Roth, et al., 1989; ALS
Δ_rH°	-144.0 ± 1.8	kJ/mol	Chyd	Rogers, Von Voithenberg, et al., 1978	liquid phase; solvent: Hexane; ALS
Δ_rH°	-134.9 ± 0.88	kJ/mol	Chyd	Turner and Meador, 1957	liquid phase; solvent: Acetic acid; ALS

( • Hydrogen ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	75. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=71.1 kJ/mol, Δ_rS(300 K)=103. J/mol*K; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	103.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=71.1 kJ/mol, Δ_rS(300 K)=103. J/mol*K; M

( • 2 Hydrogen ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	44. ± 2.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=85.8 J/mol*K; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	85.8	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=85.8 J/mol*K; M

( • 3 Hydrogen ) + = ( • 4)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	44. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=105. J/mol*K; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	101.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=105. J/mol*K; M

( • 4 Hydrogen ) + = ( • 5)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=18. kJ/mol, Δ_rS(300 K)=91.6 J/mol*K; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	94.1	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=18. kJ/mol, Δ_rS(300 K)=91.6 J/mol*K; M

( • 5 Hydrogen ) + = ( • 6)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	20. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=17. kJ/mol, Δ_rS(300 K)=99.6 J/mol*K; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	99.2	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=17. kJ/mol, Δ_rS(300 K)=99.6 J/mol*K; M

( • 6 Hydrogen ) + = ( • 7)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=3. kJ/mol; Δ_rS(300 K)=75.3 J/mol*K; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	75.3	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=3. kJ/mol; Δ_rS(300 K)=75.3 J/mol*K; M

(H₃⁺ • 3 Hydrogen ) + = (H₃⁺ • 4)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.2 ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase; M
Δ_rH°	10.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	74.9	J/mol*K	PHPMS	Hiraoka, 1987	gas phase; M
Δ_rS°	80.8	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M

(H₃⁺ • 2 Hydrogen ) + = (H₃⁺ • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13. ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase; M
Δ_rH°	16.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	77.4	J/mol*K	PHPMS	Hiraoka, 1987	gas phase; M
Δ_rS°	84.5	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M

Hydrogen + =

By formula: H₂ + C₈H₁₆ = C₈H₁₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-118.2 ± 0.4	kJ/mol	Chyd	Rogers, Dejroongruang, et al., 1992	liquid phase; solvent: Cyclohexane; ALS
Δ_rH°	-119.7 ± 2.2	kJ/mol	Chyd	Rogers and Siddiqui, 1975	liquid phase; solvent: n-Hexane; ALS
Δ_rH°	-114.6 ± 0.59	kJ/mol	Chyd	Turner, Jarrett, et al., 1973	liquid phase; solvent: Acetic acid; ALS

2 Hydrogen + =

By formula: 2H₂ + C₈H₁₄ = C₈H₁₈

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-268.7 ± 1.1	kJ/mol	Chyd	Rogers, Dagdagan, et al., 1979	liquid phase; solvent: Hexane; ALS
Δ_rH°	-262.8 ± 0.67	kJ/mol	Chyd	Turner, Jarrett, et al., 1973	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-263.	kJ/mol	Chyd	Sicher, Svoboda, et al., 1966	liquid phase; solvent: Acetic acid; ALS

Hydrogen + =

By formula: H₂ + C₈H₁₄O = C₈H₁₆O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-55.73	kJ/mol	Chyd	Wiberg, Crocker, et al., 1991	liquid phase; ALS
Δ_rH°	-53.14	kJ/mol	Chyd	Wiberg, Crocker, et al., 1991	solid phase; ALS
Δ_rH°	-39.0	kJ/mol	Chyd	Wiberg, Crocker, et al., 1991	gas phase; ALS
Δ_rH°	-53.14 ± 0.59	kJ/mol	Cm	Wiberg, Crocker, et al., 1991	solid phase; ALS

Hydrogen + =

By formula: H₂ + C₇H₁₂ = C₇H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-111.4 ± 0.37	kJ/mol	Chyd	Rogers, Crooks, et al., 1987	liquid phase; ALS
Δ_rH°	-106.3 ± 0.46	kJ/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid; ALS
Δ_rH°	-106.3 ± 0.46	kJ/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid; ALS

2 Hydrogen + =

By formula: 2H₂ + C₇H₁₀ = C₇H₁₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-208.9 ± 0.3	kJ/mol	Chyd	Turner, Mallon, et al., 1973	liquid phase; solvent: Glacial acetic acid; ALS
Δ_rH°	-212.4 ± 0.63	kJ/mol	Chyd	Conn, Kistiakowsky, et al., 1939	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -214.5 ± 0.2 kJ/mol; At 355 K; ALS

Hydrogen + =

By formula: H₂ + C₇H₁₀ = C₇H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-137. ± 0.4	kJ/mol	Chyd	Doering, Roth, et al., 1988	gas phase; ALS
Δ_rH°	-141.5 ± 1.2	kJ/mol	Chyd	Rogers, Choi, et al., 1980	liquid phase; solvent: Hexane; Author was aware that data differs from previously reported values; ALS
Δ_rH°	-138.6 ± 0.88	kJ/mol	Chyd	Turner, Meador, et al., 1957	liquid phase; solvent: Acetic acid; ALS

+ Hydrogen =

By formula: C₃H₆O + H₂ = C₃H₈O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-84.3 ± 0.4	kJ/mol	Cm	Wiberg, Crocker, et al., 1991	liquid phase; solvent: Triglyme; Heat of hydrogenation; ALS
Δ_rH°	-69.55 ± 0.76	kJ/mol	Eqk	Connett, 1972	gas phase; At 473-524 K; ALS
Δ_rH°	-65.77 ± 0.67	kJ/mol	Chyd	Buckley and Cox, 1967	gas phase; ALS

2 Hydrogen + =

By formula: 2H₂ + C₆H₈ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-224.4 ± 1.2	kJ/mol	Chyd	Turner, Mallon, et al., 1973	liquid phase; solvent: Glacial acetic acid; ALS
Δ_rH°	-229.6 ± 0.42	kJ/mol	Chyd	Kistiakowsky, Ruhoff, et al., 1936	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -231.7 ± 0.4 kJ/mol; At 355 °K; ALS

(solution) + Hydrogen (solution) = 2 (solution)

By formula: C₁₀Mn₂O₁₀ (solution) + H₂ (solution) = 2C₅HMnO₅ (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	36.4 ± 1.3	kJ/mol	EqS	Klingler R.J. and Rathke, 1992	solvent: Supercritical carbon dioxide; Temperature range: 373-463 K; MS

Henry's Law data

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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)

k°_H (mol/(kg*bar))	d(ln(k_H))/d(1/T) (K)	Method	Reference	Comment
0.00078	500.	L	N/A
0.00078	640.	Q	N/A	Only the tabulated data between T = 273. K and T = 303. K from missing citation was used to derive k_H and -Δ k_H/R. Above T = 303. K the tabulated data could not be parameterized by equation (reference missing) very well. The partial pressure of water vapor (needed to convert some Henry's law constants) was calculated using the formula given by missing citation. The quantities A and α from missing citation were assumed to be identical.
0.00078	490.	L	N/A
0.00078		R	N/A

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Ion clustering data, Mass spectrum (electron ionization), References, Notes

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
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

View reactions leading to H₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	15.42593 ± 0.00005	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	422.3	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	394.7	kJ/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
15.425927	EVAL	Shiner, Gilligan, et al., 1993	T = 0K; LL
15.425930	EVAL	Shiner, Gilligan, et al., 1993	T = 0K; LL
15.425932 ± 0.000002	S	McCormack, Gilligan, et al., 1989	T = 0K; LL
15.429558 ± 0.00001	LS	Glab and Hessler, 1987	T = 0K; LBLHLM
15.433174 ± 0.00001	LS	Glab and Hessler, 1987	T = 0K; LBLHLM
15.425942 ± 0.00001	LS	Glab and Hessler, 1987	T = 0K; LBLHLM
15.425932	S	Eyler, Short, et al., 1986	T = 0K; LBLHLM
15.425929	S	Eyler, Short, et al., 1986	T = 0K; LBLHLM
15.425930 ± 0.000027	N/A	Eyler, Short, et al., 1986	LBLHLM
15.5 ± 1.0	S	Farber, Srivastava, et al., 1982	LBLHLM
15.98	PE	Kimura, Katsumata, et al., 1981	LLK
15.43	PE	Bieri, Schmelzer, et al., 1980	LLK
15.42589	EVAL	Huber and Herzberg, 1979	LLK
16. ± 1.	EI	Farber and Srivastava, 1977	LLK
15.4	PI	Rabalais, Debies, et al., 1974	LLK
15.43	PE	Lee and Rabalais, 1974	LLK
15.42589 ± 0.00005	S	Herzberg and Jungen, 1972	LLK
15.4256 ± 0.0001	S	Takezawa, 1970	RDSH
15.38186 ± 0.00031	PE	Asbrink, 1970	RDSH
15.44 ± 0.01	EI	Lossing and Semeluk, 1969	RDSH
15.4256	S	Herzberg, 1969	RDSH
15.431 ± 0.022	TE	Villarejo, 1968	RDSH
15.439 ± 0.015	PE	Collin and Natalis, 1968	RDSH
15.43	CI	Cermak, 1968	RDSH
15.37 ± 0.05	EI	Kerwin, Marmet, et al., 1963	RDSH
15.4269 ± 0.0016	S	Beutler and Junger, 1936	RDSH

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
H⁺	18.078 ± 0.003	H	PIPECO	Weitzel, Mahnert, et al., 1994	T = 0K; LL
H⁺	18.0 ± 0.2	H	EI	Crowe and McConkey, 1973	LLK
H⁺	17.28 ± 0.16	H^-	EI	Locht and Momigny, 1971	LLK
H⁺	17.3	H^-	EI	Curran, Laboratories	RDSH

De-protonation reactions

+ = Hydrogen

By formula: H^- + H⁺ = H₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1675.3	kJ/mol	N/A	Shiell, Hu, et al., 2000	gas phase; Given: 139714.8±1 cm-1 at 0K, or 399.465±0.003 kcal/mol; B
Δ_rH°	1675.3	kJ/mol	N/A	Pratt, McCormack, et al., 1992	gas phase; 399.46±0.01 kcal/mol at 0K; 0.94 correction, Gurvich, Veyts, et al.; B
Δ_rH°	1675.3	kJ/mol	D-EA	Lykke, Murray, et al., 1991	gas phase; Reported: 6082.99±0.15 cm-1, or 0.754195(18) eV; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1649.3 ± 0.42	kJ/mol	H-TS	Shiell, Hu, et al., 2000	gas phase; Given: 139714.8±1 cm-1 at 0K, or 399.465±0.003 kcal/mol; B
Δ_rG°	1649.3	kJ/mol	H-TS	Lykke, Murray, et al., 1991	gas phase; Reported: 6082.99±0.15 cm-1, or 0.754195(18) eV; B

Ion clustering data

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

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⁺ + Hydrogen = (Ar⁺ • )

By formula: Ar⁺ + H₂ = (Ar⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	93.7	kJ/mol	FA	Shul, Passarella, et al., 1987	gas phase; switching reaction(Ar+)Ar, Δ_rH>; Dehmer and Pratt, 1982

+ Hydrogen = ( • )

By formula: CHO⁺ + H₂ = (CHO⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	16.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975, 2	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	85.8	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975, 2	gas phase

CH₅⁺ + Hydrogen = (CH₅⁺ • )

By formula: CH₅⁺ + H₂ = (CH₅⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.87 ± 0.42	kJ/mol	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	50.6	J/mol*K	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase

(CH₅⁺ • Hydrogen ) + = (CH₅⁺ • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.45 ± 0.42	kJ/mol	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	67.8	J/mol*K	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase

(CH₅⁺ • 2 Hydrogen ) + = (CH₅⁺ • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.74 ± 0.42	kJ/mol	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	94.6	J/mol*K	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase

(CH₅⁺ • 3 Hydrogen ) + = (CH₅⁺ • 4)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.57 ± 0.42	kJ/mol	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	108.	J/mol*K	PHPMS	Hiraoka, Kudaka, et al., 1991	gas phase

C₃H₇⁺ + Hydrogen = (C₃H₇⁺ • )

By formula: C₃H₇⁺ + H₂ = (C₃H₇⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1976	gas phase; Entropy change calculated or estimated, DG<, Δ_rH<
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Hiraoka and Kebarle, 1976	gas phase; Entropy change calculated or estimated, DG<, Δ_rH<

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
4.	170.	PHPMS	Hiraoka and Kebarle, 1976	gas phase; Entropy change calculated or estimated, DG<, Δ_rH<

( • ) + Hydrogen = ( • • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	95.8	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; switching reaction(Co+).2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
73. (+3.,-0.)		SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; switching reaction(Co+).2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993

( • ) + Hydrogen = ( • • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	103.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; Δ_rS(530 K)

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
83. (+3.,-0.)		SIDT	Kemper, Bushnell, et al., 1993, 2	gas phase; Δ_rS(530 K)

+ Hydrogen = ( • )

By formula: Co⁺ + H₂ = (Co⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	82. ± 4.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(O K)=76.1 kJ/mol, Δ_rS(300 K)=86.2 J/mol*K
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.0	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(O K)=76.1 kJ/mol, Δ_rS(300 K)=86.2 J/mol*K

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
73.2 (+9.6,-0.)		CID	Haynes and Armentrout, 1996	gas phase; guided ion beam CID

( • Hydrogen ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	75. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=71.1 kJ/mol, Δ_rS(300 K)=103. J/mol*K
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	103.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=71.1 kJ/mol, Δ_rS(300 K)=103. J/mol*K

( • 2 Hydrogen ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	44. ± 2.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=85.8 J/mol*K
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	85.8	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=85.8 J/mol*K

( • 3 Hydrogen ) + = ( • 4)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	44. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=105. J/mol*K
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	101.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=40. kJ/mol, Δ_rS(300 K)=105. J/mol*K

( • 4 Hydrogen ) + = ( • 5)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=18. kJ/mol, Δ_rS(300 K)=91.6 J/mol*K
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	94.1	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=18. kJ/mol, Δ_rS(300 K)=91.6 J/mol*K

( • 5 Hydrogen ) + = ( • 6)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	20. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=17. kJ/mol, Δ_rS(300 K)=99.6 J/mol*K
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	99.2	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=17. kJ/mol, Δ_rS(300 K)=99.6 J/mol*K

( • 6 Hydrogen ) + = ( • 7)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6. ± 3.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=3. kJ/mol; Δ_rS(300 K)=75.3 J/mol*K
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	75.3	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rH(0 K)=3. kJ/mol; Δ_rS(300 K)=75.3 J/mol*K

+ Hydrogen = ( • )

By formula: Fe⁺ + H₂ = (Fe⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	52.3 ± 0.8	kJ/mol	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 45.2 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	90.0	J/mol*K	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 45.2 kJ/mol

( • Hydrogen ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	71.1 ± 0.8	kJ/mol	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 65.7 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	105.	J/mol*K	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 65.7 kJ/mol

( • 2 Hydrogen ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	35. ± 0.4	kJ/mol	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 31. kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.9	J/mol*K	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 31. kJ/mol

( • 3 Hydrogen ) + = ( • 4)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	41. ± 0.4	kJ/mol	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 36. kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	104.	J/mol*K	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 36. kJ/mol

( • 4 Hydrogen ) + = ( • 5)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11. ± 0.4	kJ/mol	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 9.2 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	74.9	J/mol*K	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 9.2 kJ/mol

( • 5 Hydrogen ) + = ( • 6)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11. ± 0.4	kJ/mol	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 9.6 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	75.7	J/mol*K	SIDT	Bushnell, Kemper, et al., 1995	gas phase; Δ_rH(0K) = 9.6 kJ/mol

HN₂⁺ + Hydrogen = (HN₂⁺ • )

By formula: HN₂⁺ + H₂ = (HN₂⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	30.	kJ/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	94.6	J/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase

(HN₂⁺ • Hydrogen ) + = (HN₂⁺ • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.5	kJ/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	71.	J/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase

+ Hydrogen = ( • )

By formula: HO^- + H₂ = (HO^- • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	30.	kJ/mol	CID	Paulson and Henchman, 1984	gas phase; approximate value

HO₂⁺ + Hydrogen = (HO₂⁺ • )

By formula: HO₂⁺ + H₂ = (HO₂⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	52.3	kJ/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.	J/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase

(HO₂⁺ • ) + Hydrogen = (HO₂⁺ • • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	17.	kJ/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	71.	J/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase

H₃⁺ + Hydrogen = (H₃⁺ • )

By formula: H₃⁺ + H₂ = (H₃⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	29. ± 2.	kJ/mol	AVG	N/A	Average of 4 out of 11 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	72.8 to 72.8	J/mol*K	RNG	N/A	Range of 6 values; Individual data points

(H₃⁺ • Hydrogen ) + = (H₃⁺ • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14. ± 0.8	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Δ_rH°	13.	kJ/mol	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase
Δ_rH°	14.	kJ/mol	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase; deuterated
Δ_rH°	17.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase
Δ_rH°	7.5	kJ/mol	HPMS	Bennett and Field, 1972	gas phase; Entropy change is questionable
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	72.8	J/mol*K	PHPMS	Hiraoka, 1987	gas phase
Δ_rS°	70.7	J/mol*K	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase
Δ_rS°	67.4	J/mol*K	HPMS	Beuhler, Ehrenson, et al., 1983	gas phase; deuterated
Δ_rS°	82.8	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase
Δ_rS°	45.2	J/mol*K	HPMS	Bennett and Field, 1972	gas phase; Entropy change is questionable

(H₃⁺ • 2 Hydrogen ) + = (H₃⁺ • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13. ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Δ_rH°	16.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	77.4	J/mol*K	PHPMS	Hiraoka, 1987	gas phase
Δ_rS°	84.5	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase

(H₃⁺ • 3 Hydrogen ) + = (H₃⁺ • 4)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.2 ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Δ_rH°	10.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	74.9	J/mol*K	PHPMS	Hiraoka, 1987	gas phase
Δ_rS°	80.8	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase

(H₃⁺ • 4 Hydrogen ) + = (H₃⁺ • 5)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.9 ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.1	J/mol*K	PHPMS	Hiraoka, 1987	gas phase

(H₃⁺ • 5 Hydrogen ) + = (H₃⁺ • 6)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.4 ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	83.7	J/mol*K	PHPMS	Hiraoka, 1987	gas phase

(H₃⁺ • 6 Hydrogen ) + = (H₃⁺ • 7)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.7 ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	69.0	J/mol*K	PHPMS	Hiraoka, 1987	gas phase

(H₃⁺ • 7 Hydrogen ) + = (H₃⁺ • 8)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.3 ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	74.9	J/mol*K	PHPMS	Hiraoka, 1987	gas phase

(H₃⁺ • 8 Hydrogen ) + = (H₃⁺ • 9)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.6 ± 0.4	kJ/mol	PHPMS	Hiraoka, 1987	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.9	J/mol*K	PHPMS	Hiraoka, 1987	gas phase

+ Hydrogen = ( • )

By formula: H₃O⁺ + H₂ = (H₃O⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	15. ± 2.	kJ/mol	SCATTERING	Okumura, Yeh, et al., 1990	gas phase

+ Hydrogen = ( • )

By formula: K⁺ + H₂ = (K⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.78	kJ/mol	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 6.07 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	56.5	J/mol*K	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 6.07 kJ/mol

( • Hydrogen ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.15	kJ/mol	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 5.65 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	46.9	J/mol*K	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 5.65 kJ/mol

+ Hydrogen = ( • )

By formula: Li⁺ + H₂ = (Li⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	27. ± 19.	kJ/mol	EI	Wu, 1979	gas phase

+ Hydrogen = ( • )

By formula: Na⁺ + H₂ = (Na⁺ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.3	kJ/mol	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 10.3 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	55.2	J/mol*K	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 10.3 kJ/mol

( • Hydrogen ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.1	kJ/mol	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 9.41 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	51.9	J/mol*K	SIDT	Bushnell, Kemper, et al., 1994	gas phase; Δ_rH(0K) = 9.41 kJ/mol

Mass spectrum (electron ionization)

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

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

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NIST MS number	245692

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References

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), Notes

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]

Rathke, Klingler, et al., 1992
Rathke, J.W.; Klingler, R.J.; Krause, T.R., Organometallics, 1992, 11, 585. [all data]

Bor, 1986
Bor, G., Pure & Appl. Chem., 1986, 58, 543. [all data]

Alemdaroglu, Penninger, et al., 1976
Alemdaroglu, N.H.; Penninger, J.M.L.; Oltay, E., Monatsh. Chem., 1976, 107, 1043. [all data]

Ungváry, 1972
Ungváry, F., J. Organometal. Chem., 1972, 36, 363. [all data]

Poë, Sampson, et al., 1993
Poë, A.J.; Sampson, C.N.; Smith, R.T.; Zheng, Y., J. Am. Chem. Soc., 1993, 115, 3174. [all data]

Landrum and Hoff, 1985
Landrum, J.T.; Hoff, C.D., J. Organometal. Chem., 1985, 282, 215. [all data]

Pedley, 1994
Pedley, J.B., Thermodynamic Data and Structures of Organic Compounds; Thermodynamics Research Center Data Series, Vol I, Thermodynamics Research Center, College Station, 1994. [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
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]

Shiell, Hu, et al., 2000
Shiell, R.C.; Hu, X.K.; Hu, Q.C.J.; Hepburn, J.W., Threshold Ion-pair Production spectroscopy (TIPPS) of H2 and D2, Faraday Disc. Chem. Soc., 2000, 115, 331, https://doi.org/10.1039/a909428h . [all data]

Pratt, McCormack, et al., 1992
Pratt, S.T.; McCormack, E.F.; Dehmer, J.L.; Dehmer, P.M., Field-Induced Ion-Pair Formation in Molecular Hydrogen, Phys. Rev. Lett., 1992, 68, 5, 584, https://doi.org/10.1103/PhysRevLett.68.584 . [all data]

Gurvich, Veyts, et al.
Gurvich, L.V.; Veyts, I.V.; Alcock, C.B., Hemisphere Publishing, NY, 1989, V. 1 2, Thermodynamic Properties of Individual Substances, 4th Ed. [all data]

Lykke, Murray, et al., 1991
Lykke, K.R.; Murray, K.K.; Lineberger, W.C., Threshold Photodetachment of H-, Phys. Rev. A, 1991, 43, 11, 6104, https://doi.org/10.1103/PhysRevA.43.6104 . [all data]

Allinger, Dodziuk, et al., 1982
Allinger, N.L.; Dodziuk, H.; Rogers, D.W.; Naik, S.N., Heats of hydrogenation and formation of some 5-membered ring compounds by molecular mechanics calculations and direct measurements, Tetrahedron, 1982, 38, 1593-1597. [all data]

Roth and Lennartz, 1980
Roth, W.R.; Lennartz, H.W., Heats of hydrogenation. I. Determination of heats of hydrogenation with an isothermal titration calorimeter, Chem. Ber., 1980, 113, 1806-1817. [all data]

Turner, Jarrett, et al., 1973
Turner, R.B.; Jarrett, A.D.; Goebel, P.; Mallon, B.J., Heats of hydrogenation. 9. Cyclic acetylenes and some miscellaneous olefins, J. Am. Chem. Soc., 1973, 95, 790-792. [all data]

Rogers and McLafferty, 1971
Rogers, D.W.; McLafferty, F.J., A new hydrogen calorimeter. Heats of hydrogenation of allyl and vinyl unsaturation adjacent to a ring, Tetrahedron, 1971, 27, 3765-3775. [all data]

Dolliver, Gresham, et al., 1937
Dolliver, M.a.; Gresham, T.L.; Kistiakowsky, G.B.; Vaughan, W.E., Heats of organic reactions. V. Heats of hydrogenation of various hydrocarbons, J. Am. Chem. Soc., 1937, 59, 831-841. [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]

Doering, Roth, et al., 1989
Doering, W.E.; Roth, W.R.; Bauer, F.; Breuckmann, R.; Ebbrecht, T.; Herbold, M.; Schmidt, R.; Lennartz, H-W.; Lenoir, D.; Boese, R., Rotational barriers of strained olefines, Chem. Ber., 1989, 122, 1263-1266. [all data]

Rogers, Von Voithenberg, et al., 1978
Rogers, D.W.; Von Voithenberg, H.; Allinger, N.L., Heats of hydrogenation of the cis and trans isomers of cyclooctene, J. Org. Chem., 1978, 43, 360-361. [all data]

Turner and Meador, 1957
Turner, R.B.; Meador, W.R., Heats of hydrogenation. IV. Hydrogenation of some cis- and trans-cycloolefins, J. Am. Chem. Soc., 1957, 79, 4133-4136. [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]

Wang, Rosini, et al., 1995
Wang, K.; Rosini, G.P.; Nolan, S.P.; Goldman, A.S., J. Am. Chem. Soc., 1995, 117, 5082. [all data]

Rogers, Crooks, et al., 1987
Rogers, D.W.; Crooks, E.; Dejroongruang, K., Enthalpies of hydrogenation of the hexenes, J. Chem. Thermodyn., 1987, 19, 1209-1215. [all data]

Turner and Garner, 1958
Turner, R.B.; Garner, R.H., Heats of hydrogenation. V. Relative stabilities in certain exocyclic-endocyclic olefin pairs, J. Am. Chem. Soc., 1958, 80, 1424-1430. [all data]

Turner and Garner, 1957
Turner, R.B.; Garner, R.H., Heats of hydrogenation. V. Relative stabilities in certain exocyclic-endocyclic olefin pairs, J. Am. Chem. Soc., 1957, 80, 1424-1430. [all data]

Turner and Garner, 1957, 2
Turner, R.B.; Garner, R.H., The stability relationship of 1-methyl-cyclopentene and methylenecyclopentane, J. Am. Chem. Soc., 1957, 79, 253. [all data]

Fang and Rogers, 1992
Fang, W.; Rogers, D.W., Enthalpy of hydrogenation of the hexadienes and cis- and trans-1,3,5-hexatriene, J. Org. Chem., 1992, 57, 2294-2297. [all data]

Molnar, Rachford, et al., 1984
Molnar, A.; Rachford, R.; Smith, G.V.; Liu, R., Heats of hydrogenation by a simple and rapid flow calorimetric method, Appl. Catal., 1984, 9, 219-223. [all data]

Turner, Mallon, et al., 1973
Turner, R.B.; Mallon, B.J.; Tichy, M.; Doering, W.v.E.; Roth, W.R.; Schroder, G., Heats of hydrogenation. X. Conjugative interaction in cyclic dienes and trienes, J. Am. Chem. Soc., 1973, 95, 8605-8610. [all data]

Kistiakowsky, Ruhoff, et al., 1936
Kistiakowsky, G.B.; Ruhoff, J.R.; Smith, H.A.; Vaughan, W.E., Heats of organic reactions. IV. Hydrogenation of some dienes and of benzene, J. Am. Chem. Soc., 1936, 58, 146-153. [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 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]

Rogers and Skanupong, 1974
Rogers, D.W.; Skanupong, S., Heats of hydrogenation of sixteen terminal monoolefins. The alternating effect, J. Phys. Chem., 1974, 78, 2569-2572. [all data]

Turner, Meador, et al., 1957
Turner, R.B.; Meador, W.R.; Winkler, R.E., Heats of hydrogenation. I. Apparatus and the heats of hydrogenation of bicyclo[2,2,1]heptene, bicyclo[2,2,1]heptadiene, bicyclo[2,2,2]octene and bicyclo[2,2,2]octadiene, J. Am. Chem. Soc., 1957, 79, 4116-4121. [all data]

Roth, Klaerner, et al., 1983
Roth, W.R.; Klaerner, F.G.; Gerit, F.; Grimme, W.; Koeser, H.G.; Busch, R.; Muskulus, B.; Breuckmann, R.; Scholz, B.P.; Lennartz, H.W., Stereochemistry of the bicyclo[2.1.0]pentane ring opening: thermolysis of tricyclo[3.2.0.0(,)]heptane derivatives, Chem. Ber., 1983, 116, 2717-2737. [all data]

Hales and Herington, 1957
Hales, J.L.; Herington, E.F.G., Equilibrium between pyridine and piperidine, Trans. Faraday Soc., 1957, 53, 616-622. [all data]

Burrows and King, 1935
Burrows, G.H.; King, L.A., Jr., The free energy change that accompanies hydrogenation of pyridine to piperidine, J. Am. Chem. Soc., 1935, 57, 1789-1791. [all data]

Turner, Nettleton, et al., 1958
Turner, R.B.; Nettleton, J.E.; Perelman, Heats of Hydrogenation. VI. Heats of hydrogenation of some substituted ethylenes, J. Am. Chem. Soc., 1958, 80, 1430-1433. [all data]

Crawford and Parks, 1936
Crawford, B.L., Jr.; Parks, G.S., The heat of hydrogenation of diisobutylene, J. Am. Chem. Soc., 1936, 58, 373. [all data]

Kistiakowsky and Nickle, 1951
Kistiakowsky, G.B.; Nickle, A.G., Ethane-ethylene and propane-propylene equilibria, Faraday Discuss. Chem. Soc., 1951, 10, 175-187. [all data]

Kistiakowsky, Ruhoff, et al., 1935
Kistiakowsky, G.B.; Ruhoff, J.R.; Smith, H.A.; Vaughan, W.E., Heats of organic reactions. II. Hydrogenation of some simpler olefinic hydrocarbons, J. Am. Chem. Soc., 1935, 57, 876-882. [all data]

Kemper, Bushnell, et al., 1993, 2
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]

Wiberg, Crocker, et al., 1991
Wiberg, K.B.; Crocker, L.S.; Morgan, K.M., Thermochemical studies of carbonyl compounds. 5. Enthalpies of reduction of carbonyl groups, J. Am. Chem. Soc., 1991, 113, 3447-3450. [all data]

Buckley and Herington, 1965
Buckley, E.; Herington, E.F.G., Equilibria in some secondary alcohol + hydrogen + ketone systems, Trans. Faraday Soc., 1965, 61, 1618-1625. [all data]

Dolliver, Gresham, et al., 1938
Dolliver, M.A.; Gresham, T.L.; Kistiakowsky, G.B.; Smith, E.A.; Vaughan, W.E., Heats of organic reactions. VI. Heats of hydrogenation of some oxygen-containing compounds, J. Am. Chem. Soc., 1938, 60, 440-450. [all data]

Roth, Adamczak, et al., 1991
Roth, W.R.; Adamczak, O.; Breuckmann, R.; Lennartz, H.-W.; Boese, R., Die Berechnung von Resonanzenergien; das MM2ERW-Kraftfeld, Chem. Ber., 1991, 124, 2499-2521. [all data]

Rogers, Dejroongruang, et al., 1992
Rogers, D.W.; Dejroongruang, K.; Samuel, S.D.; Fang, W.; Zhao, Y., Enthalpies of hydrogenation of the octenes and the methylheptenes, J. Chem. Thermodyn., 1992, 24, 561-565. [all data]

Rogers and Siddiqui, 1975
Rogers, D.W.; Siddiqui, N.A., Heats of hydrogenation of large molecules. I. Esters of unsaturated fatty acids, J. Phys. Chem., 1975, 79, 574-577. [all data]

Rogers, Dagdagan, et al., 1979
Rogers, D.W.; Dagdagan, O.A.; Allinger, N.L., Heats of hydrogenation and formation of linear alkynes and a molecular mechanics interpretation, J. Am. Chem. Soc., 1979, 101, 671-676. [all data]

Sicher, Svoboda, et al., 1966
Sicher, J.; Svoboda, M.; Zavada, J.; Turner, R.B.; Goebel, P., Sterochemical studies - XXXVI. An approach to conformational analysis of medium ring compounds. Unsaturated ten-membered ring derivates, Tetrahedron, 1966, 22, 659-671. [all data]

Doering, Roth, et al., 1988
Doering, W.E.; Roth, W.R.; Breuckmann, R.; Figge, L.; Lennartz, H.-W.; Fessner, W.-D.; Prinzbach, F.H., Verbotene Reaktionen. - [2 + 2]-Cycloreversion starrer Cyclobutane, Chem. Ber., 1988, 121, 1-9. [all data]

Rogers, Choi, et al., 1980
Rogers, D.W.; Choi, L.S.; Girellini, R.S., Heats of hydrogenation and formation of quadricyclene, norbornadiene, norbornene, and nortricyclene, J. Phys. Chem., 1980, 84, 1810-1814. [all data]

Connett, 1972
Connett, J.E., Chemical equilibria. 5. Measurement of equilibrium constants for the dehydrogenation of propanol by a vapour flow technique, J. Chem. Thermodyn., 1972, 4, 233-237. [all data]

Buckley and Cox, 1967
Buckley, E.; Cox, J.D., Chemical equilibria. Part 2.-Dehydrogenation of propanol and butanol, Trans. Faraday Soc., 1967, 63, 895-901. [all data]

Klingler R.J. and Rathke, 1992
Klingler R.J.; Rathke, J.W., Inorg. Chem., 1992, 31, 804. [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]

Shiner, Gilligan, et al., 1993
Shiner, D.; Gilligan, J.M.; Cook, B.M.; Lichten, W., H₂, D₂, and HD ionization potentials by accurate calibration of several iodine lines, Phys. Rev. A, 1993, 47, 4042. [all data]

McCormack, Gilligan, et al., 1989
McCormack, E.; Gilligan, J.M.; Cornaggia, C.; Eyler, E.E., Measurement of high Rydberg states and the ionization potential of H₂, Phys. Rev. A, 1989, 39, 2260. [all data]

Glab and Hessler, 1987
Glab, W.L.; Hessler, J.P., Multiphoton excitation of high singlet np Rydberg states of molecular hydrogen: Spectroscopy and dynamics, Phys. Rev. A, 1987, 35, 2102. [all data]

Eyler, Short, et al., 1986
Eyler, E.E.; Short, R.C.; Pipkin, F.M., Precision spectroscopy of the nf triplet Rydberg states of H₂ and determination of the triplet ionization potential, Phys. Rev. Lett., 1986, 56, 2602. [all data]

Farber, Srivastava, et al., 1982
Farber, M.; Srivastava, R.D.; Moyer, J.W., Mass spectrometric determination of the thermodynamics of potassium hydroxide and minor potassium-containing species required in magnetohydrodynamic power systems, J. Chem. Thermodyn., 1982, 14, 1103. [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]

Bieri, Schmelzer, et al., 1980
Bieri, G.; Schmelzer, A.; Asbrink, L.; Jonsson, M., Fluorine and the fluoroderivatives of acetylene and diacetylene studied by 30.4 nm He(II) photoelectron spectroscopy, Chem. Phys., 1980, 49, 213. [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]

Farber and Srivastava, 1977
Farber, M.; Srivastava, R.D., Mass spectrometric determination of the heats of formation of the silane fluorides, Chem. Phys. Lett., 1977, 51, 307. [all data]

Rabalais, Debies, et al., 1974
Rabalais, J.W.; Debies, T.P.; Berkosky, J.L.; Huang, J.-T.J.; Ellison, F.O., Calculated photoionization cross sections relative experimental photoionization intensities for a selection of small molecules, J. Chem. Phys., 1974, 61, 516. [all data]

Lee and Rabalais, 1974
Lee, T.H.; Rabalais, J.W., Vibrational transition probabilities in photoelectron spectra, J. Chem. Phys., 1974, 61, 2747. [all data]

Herzberg and Jungen, 1972
Herzberg, G.; Jungen, Ch., Rydberg series and ionization potential of the H₂ molecule, J. Mol. Spectrosc., 1972, 41, 425. [all data]

Takezawa, 1970
Takezawa, S., Absorption spectrum of H₂ in the vacuum-uv region. II. Rydberg series converging to the first six vibrational levels of the H₂⁺ ground state, J. Chem. Phys., 1970, 52, 5793. [all data]

Asbrink, 1970
Asbrink, L., The photoelectron spectrum of H₂, Chem. Phys. Lett., 1970, 7, 549. [all data]

Lossing and Semeluk, 1969
Lossing, F.P.; Semeluk, G.P., Threshold ionization efficiency curves for monoenergetic electron impact on H₂, D₂, CH₄ and CD₄, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 408. [all data]

Herzberg, 1969
Herzberg, G., Dissociation energy and ionization potential of molecular hydrogen, Phys. Rev. Letters, 1969, 23, 1081. [all data]

Villarejo, 1968
Villarejo, D., Measurement of threshold electrons in the photoionization of H₂ and D₂, J. Chem. Phys., 1968, 48, 4014. [all data]

Collin and Natalis, 1968
Collin, J.E.; Natalis, P., Vibrational and electronic ionic states of nitric oxide. An accurate method for measuring ionization potentials by photoelectron spectroscopy, Intern. J. Mass Spectrom. Ion Phys., 1968, 1, 483. [all data]

Cermak, 1968
Cermak, V., Penning ionization electron spectroscopy. I. Determination of ionization potentials of polyatomic molecules, Collection Czech. Chem. Commun., 1968, 33, 2739. [all data]

Kerwin, Marmet, et al., 1963
Kerwin, L.; Marmet, P.; Clarke, E.M., Recent work with the electrostatic electron selector, Advan. Mass Spectrom., 1963, 2, 522. [all data]

Beutler and Junger, 1936
Beutler, H.; Junger, H.-O., Uber das Absorptionsspektrum des Wasserstoffs. III. Die Autoionisierung im Term 3pπ 1u des H₂ und ihre Auswahlgesetze. Bestimmung der lonisierungsenergie des H₂, Z. Physik, 1936, 100, 80. [all data]

Weitzel, Mahnert, et al., 1994
Weitzel, K.-M.; Mahnert, J.; Penno, M., ZEKE-PEPICO investigations of dissociation energies in ionic reactions, Chem. Phys. Lett., 1994, 224, 371. [all data]

Crowe and McConkey, 1973
Crowe, A.; McConkey, J.W., Dissociative ionization by electron impact. I. Protons from H₂, J. Phys. B:, 1973, 6, 2088. [all data]

Locht and Momigny, 1971
Locht, R.; Momigny, J., Mass spectrometric study of ion-pair processes in diatomic molecules: H₂, CO, NO and O₂, Int. J. Mass Spectrom. Ion Phys., 1971, 7, 121. [all data]

Curran, Laboratories
Curran, R.K., Negative ion formation in various gases at pressures up to .5 mm of Hg, Scientific Paper 62-908-113-P7, Westinghouse Research, Laboratories, Pittsburgh, 1962. [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, 2
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]

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]

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

Symbols used in this document:

AE	Appearance energy
IE (evaluated)	Recommended ionization energy
P_c	Critical pressure
P_triple	Triple point pressure
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
T	Temperature
T_c	Critical temperature
T_triple	Triple point temperature
d(ln(k_H))/d(1/T)	Temperature dependence parameter for Henry's Law constant
k°_H	Henry's Law constant at 298.15K
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_rS°	Entropy of reaction at standard conditions
ρ_c	Critical density

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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NIST Chemistry WebBook, SRD 69

Hydrogen

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Gas Phase Heat Capacity (Shomate Equation)

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Antoine Equation Parameters

Reaction thermochemistry data

Reactions 1 to 50

Free energy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Henry's Law data

Henry's Law constant (water solution)

Gas phase ion energetics data

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

Ion clustering data

Clustering reactions

Free energy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Mass spectrum (electron ionization)

Spectrum

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