Oxygen

Formula: O₂
Molecular weight: 31.9988
IUPAC Standard InChI: InChI=1S/O2/c1-2
IUPAC Standard InChIKey: MYMOFIZGZYHOMD-UHFFFAOYSA-N
CAS Registry Number: 7782-44-7
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript.
Other names: Molecular oxygen; Oxygen molecule; Pure oxygen; O2; Liquid oxygen; UN 1072; UN 1073; Dioxygen
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Information on this page:
Other data available:
- Phase change data
- Reaction thermochemistry data: reactions 51 to 70
- Henry's Law data
- Mass spectrum (electron ionization)
- Constants of diatomic molecules
- Fluid Properties
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Gas phase thermochemistry data

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, References, Notes

Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	49.033 ± 0.001	cal/mol*K	Review	Cox, Wagman, et al., 1984	CODATA Review value
S°_{gas,1 bar}	49.032	cal/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 (cal/mol*K)
H° = standard enthalpy (kcal/mol)
S° = standard entropy (cal/mol*K)
t = temperature (K) / 1000.

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View table.

Temperature (K)	100. to 700.	700. to 2000.	2000. to 6000.
A	7.486219	7.177904	4.997876
B	-4.836356	2.096791	2.562312
C	13.83041	-0.953187	-0.482910
D	-8.725201	0.188411	0.035002
E	-0.001762	-0.177246	2.209781
F	-2.127981	-2.706664	1.275730
G	58.98530	56.44510	56.79219
H	0.0	0.0	0.0
Reference	Chase, 1998	Chase, 1998	Chase, 1998
Comment	Data last reviewed in March, 1977; New parameter fit January 2009	Data last reviewed in March, 1977; New parameter fit January 2009	Data last reviewed in March, 1977; New parameter fit January 2009

Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Ion clustering data, References, Notes

Data compiled as indicated in comments:
B - John E. Bartmess
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

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

+ Oxygen = ( • Oxygen )

By formula: O₂^- + O₂ = (O₂^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12. ± 4.	kcal/mol	AVG	N/A	Average of 5 out of 7 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	32.	cal/mol*K	PHPMS	Conway and Nesbit, 1968	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.2 ± 1.1	kcal/mol	TDAs	Hiraoka, 1888	gas phase; see also Sherwood, Hanold, et al., 1996. Aquino, Taylor, et al., 2001 calns indicate rectangular anion; B
Δ_rG°	5.4 ± 1.0	kcal/mol	IMRE	Payzant J.D. and Kebarle, 1972	gas phase; B
Δ_rG°	3.2 ± 1.0	kcal/mol	IMRE	Pack and Phelps, 1971	gas phase; B
Δ_rG°	4.00 ± 0.50	kcal/mol	IMRE	Parkes, 1971	gas phase; B
Δ_rG°	3.8 ± 1.0	kcal/mol	TDAs	Conway and Nesbit, 1968	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.5	300.	DT	Pack and Phelps, 1971	gas phase; M

+ Oxygen = ( • Oxygen )

By formula: O₂⁺ + O₂ = (O₂⁺ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10. ± 1.	kcal/mol	AVG	N/A	Average of 5 out of 6 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.8	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	25.02	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M
Δ_rS°	20.	cal/mol*K	PHPMS	Durden, Kebarle, et al., 1969	gas phase; M
Δ_rS°	20.6	cal/mol*K	PHPMS	Yang and Conway, 1964	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.8	300.	DT	Rakshit and Warneck, 1981	gas phase; M
3.3	300.	DT	Rakshit and Warneck, 1980	gas phase; M
3.4	296.	FA	Howard, Bierbaum, et al., 1972	gas phase; M
5.9	200.	FA	Adams and Bohme, 1970	gas phase; M

(HO₂⁺ • 2 Oxygen ) + Oxygen = (HO₂⁺ • 3 Oxygen )

By formula: (HO₂⁺ • 2O₂) + O₂ = (HO₂⁺ • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.7 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	3.2	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.3	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	20.	cal/mol*K	N/A	Hiraoka, Saluja, et al., 1979	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
1.1	105.	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; Entropy change calculated or estimated; M

( • 7 • Oxygen ) + = ( • 8 • Oxygen )

By formula: (O₂^- • 7N₂ • O₂) + N₂ = (O₂^- • 8N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.6 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Δ_rH°	1.53	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.9	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M
Δ_rS°	18.0	cal/mol*K	N/A	Hiraoka, 1988, 2	gas phase; Entropy change calculated or estimated; M

O^- + Oxygen = (O^- • Oxygen )

By formula: O^- + O₂ = (O^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	32.	kcal/mol	PDiss	Hiller and Vestal, 1981	gas phase; From thermochemical cycle, Δ_rH<; M
Δ_rH°	39.0	kcal/mol	PES	Novich, Engelking, et al., 1979	gas phase; From thermochemical cycle, from EA(O3), D(O-O2) AND EA(O); M
Δ_rH°	38.	kcal/mol	PDiss	Cosby, Moseley, et al., 1978	gas phase; M
Δ_rH°	42.	kcal/mol	CID	Lifschitz, Wu, et al., 1978	gas phase; M

( • Oxygen ) + Oxygen = ( • 2 Oxygen )

By formula: (O₂⁺ • O₂) + O₂ = (O₂⁺ • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	5.9 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	6.87 ± 0.06	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	26.3	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	31.78	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

(HO₂⁺ • Oxygen ) + Oxygen = (HO₂⁺ • 2 Oxygen )

By formula: (HO₂⁺ • O₂) + O₂ = (HO₂⁺ • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.9 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	6.6	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	22.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

( • 3 Oxygen ) + Oxygen = ( • 4 Oxygen )

By formula: (O₂⁺ • 3O₂) + O₂ = (O₂⁺ • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.1 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	2.46 ± 0.18	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.2	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	23.9	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

( • 2 Oxygen ) + Oxygen = ( • 3 Oxygen )

By formula: (O₂⁺ • 2O₂) + O₂ = (O₂⁺ • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.5 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	2.5 ± 0.1	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.7	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	19.8	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

( • 4 Oxygen ) + Oxygen = ( • 5 Oxygen )

By formula: (O₂⁺ • 4O₂) + O₂ = (O₂⁺ • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.9 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	1.8 ± 0.7	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	17.0	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

O₃^- + Oxygen = (O₃^- • Oxygen )

By formula: O₃^- + O₂ = (O₃^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.10 ± 0.20	kcal/mol	TDAs	Hiraoka, 1988, 2	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.0	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-3.60 ± 0.50	kcal/mol	TDAs	Hiraoka, 1988, 2	gas phase; B

+ Oxygen = ( • Oxygen )

By formula: NO^- + O₂ = (NO^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.9 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	14.5	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
-0.4	200.	FA	Dunkin, Fehsenfeld, et al., 1971	gas phase; DG>; M

( • 6 Oxygen ) + Oxygen = ( • 7 Oxygen )

By formula: (O₂^- • 6O₂) + O₂ = (O₂^- • 7O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.40	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.	cal/mol*K	N/A	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M

( • 7 Oxygen ) + Oxygen = ( • 8 Oxygen )

By formula: (O₂⁺ • 7O₂) + O₂ = (O₂⁺ • 8O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.82	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.	cal/mol*K	N/A	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M

( • Oxygen ) + = ( • • Oxygen )

By formula: (O₂⁺ • O₂) + N₂ = (O₂⁺ • N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.9	kcal/mol	HPMS	Speller and Fitaire, 1983	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	10.1	cal/mol*K	HPMS	Speller and Fitaire, 1983	gas phase; Entropy change is questionable; M

(H₃⁺ • Oxygen ) + Oxygen = (H₃⁺ • 2 Oxygen )

By formula: (H₃⁺ • O₂) + O₂ = (H₃⁺ • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.5	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M

(O₃^- • 4 Oxygen ) + Oxygen = (O₃^- • 5 Oxygen )

By formula: (O₃^- • 4O₂) + O₂ = (O₃^- • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.54	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; Δ_rH, Δ_rS approximate; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.4	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; Δ_rH, Δ_rS approximate; M

H₃⁺ + Oxygen = (H₃⁺ • Oxygen )

By formula: H₃⁺ + O₂ = (H₃⁺ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.5	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.6	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M

(O₂S^- • 2 • Oxygen ) + = (O₂S^- • 3 • Oxygen )

By formula: (O₂S^- • 2O₂S • O₂) + O₂S = (O₂S^- • 3O₂S • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.60 ± 0.40	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.5 ± 3.0	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • • Oxygen ) + = (O₂S^- • 2 • Oxygen )

By formula: (O₂S^- • O₂S • O₂) + O₂S = (O₂S^- • 2O₂S • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.60 ± 0.40	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	2.5 ± 2.0	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₃S^- • • Oxygen ) + = (O₃S^- • 2 • Oxygen )

By formula: (O₃S^- • O₂S • O₂) + O₂S = (O₃S^- • 2O₂S • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	5.70 ± 0.60	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.6 ± 2.1	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

+ Oxygen = ( • Oxygen )

By formula: O⁺ + O₂ = (O⁺ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	42.9	kcal/mol	PDiss	Hiller and Vestal, 1982	gas phase; M
Δ_rH°	48.	kcal/mol	PI	Linn, Ono, et al., 1981	gas phase; M
Δ_rH°	49.9	kcal/mol	PDiss	Mosely, Ozenne, et al., 1981	gas phase; M

(O₃S^- • Oxygen ) + = (O₃S^- • • Oxygen )

By formula: (O₃S^- • O₂) + O₂S = (O₃S^- • O₂S • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.50 ± 0.80	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	4.4 ± 2.2	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • Oxygen ) + = (O₂S^- • • Oxygen )

By formula: (O₂S^- • O₂) + O₂S = (O₂S^- • O₂S • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.0 ± 1.0	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	6.2 ± 2.2	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

( • 2 • Oxygen ) + = ( • 3 • Oxygen )

By formula: (O₂^- • 2N₂ • O₂) + N₂ = (O₂^- • 3N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.5 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.3	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

( • 3 • Oxygen ) + = ( • 4 • Oxygen )

By formula: (O₂^- • 3N₂ • O₂) + N₂ = (O₂^- • 4N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.2 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.7	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

( • 4 • Oxygen ) + = ( • 5 • Oxygen )

By formula: (O₂^- • 4N₂ • O₂) + N₂ = (O₂^- • 5N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.9 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.5	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

( • 5 • Oxygen ) + = ( • 6 • Oxygen )

By formula: (O₂^- • 5N₂ • O₂) + N₂ = (O₂^- • 6N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.8 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.5	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

( • 6 • Oxygen ) + = ( • 7 • Oxygen )

By formula: (O₂^- • 6N₂ • O₂) + N₂ = (O₂^- • 7N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.7 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.8	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

( • • Oxygen ) + = ( • 2 • Oxygen )

By formula: (O₂^- • N₂ • O₂) + N₂ = (O₂^- • 2N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.8 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.9	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

( • 2 Oxygen ) + Oxygen = ( • 3 Oxygen )

By formula: (NO^- • 2O₂) + O₂ = (NO^- • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.8 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.7	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

( • 3 Oxygen ) + Oxygen = ( • 4 Oxygen )

By formula: (NO^- • 3O₂) + O₂ = (NO^- • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.1	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

( • 4 Oxygen ) + Oxygen = ( • 5 Oxygen )

By formula: (NO^- • 4O₂) + O₂ = (NO^- • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.2	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

( • Oxygen ) + Oxygen = ( • 2 Oxygen )

By formula: (NO^- • O₂) + O₂ = (NO^- • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.9 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.7	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

(HO₂⁺ • 3 Oxygen ) + Oxygen = (HO₂⁺ • 4 Oxygen )

By formula: (HO₂⁺ • 3O₂) + O₂ = (HO₂⁺ • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.5 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 4 Oxygen ) + Oxygen = (HO₂⁺ • 5 Oxygen )

By formula: (HO₂⁺ • 4O₂) + O₂ = (HO₂⁺ • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.2 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.9	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 5 Oxygen ) + Oxygen = (HO₂⁺ • 6 Oxygen )

By formula: (HO₂⁺ • 5O₂) + O₂ = (HO₂⁺ • 6O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.0 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.3	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 6 Oxygen ) + Oxygen = (HO₂⁺ • 7 Oxygen )

By formula: (HO₂⁺ • 6O₂) + O₂ = (HO₂⁺ • 7O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.0 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.5	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 7 Oxygen ) + Oxygen = (HO₂⁺ • 8 Oxygen )

By formula: (HO₂⁺ • 7O₂) + O₂ = (HO₂⁺ • 8O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.8 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 8 Oxygen ) + Oxygen = (HO₂⁺ • 9 Oxygen )

By formula: (HO₂⁺ • 8O₂) + O₂ = (HO₂⁺ • 9O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.7 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.6	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • Oxygen ) + = (HO₂⁺ • • Oxygen )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.0	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

( • Oxygen ) + = ( • • Oxygen )

By formula: (O₂^- • O₂) + N₂ = (O₂^- • N₂ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.9 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.5	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

2 + Oxygen = 2

By formula: 2C₂H₆S + O₂ = 2C₂H₆OS

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-66.36 ± 0.20	kcal/mol	Cm	Douglas, 1946	liquid phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -66.5 ± 0.2 kcal/mol; At 291°K; ALS

= + 0.5 Oxygen

By formula: C₂H₆O₂S = C₂H₆OS + 0.5O₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	58.16 ± 0.20	kcal/mol	Cm	Douglas, 1946	liquid phase; Reanalyzed by Cox and Pilcher, 1970, Original value = 59.0 ± 0.2 kcal/mol; At 291°K; ALS

( • 2 Oxygen ) + Oxygen = ( • 3 Oxygen )

By formula: (O₂^- • 2O₂) + O₂ = (O₂^- • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.3	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 3 Oxygen ) + Oxygen = ( • 4 Oxygen )

By formula: (O₂^- • 3O₂) + O₂ = (O₂^- • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.8 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 4 Oxygen ) + Oxygen = ( • 5 Oxygen )

By formula: (O₂^- • 4O₂) + O₂ = (O₂^- • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.5 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 5 Oxygen ) + Oxygen = ( • 6 Oxygen )

By formula: (O₂^- • 5O₂) + O₂ = (O₂^- • 6O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.5 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.2	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 5 Oxygen ) + Oxygen = ( • 6 Oxygen )

By formula: (O₂⁺ • 5O₂) + O₂ = (O₂⁺ • 6O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.9 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.7	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 6 Oxygen ) + Oxygen = ( • 7 Oxygen )

By formula: (O₂⁺ • 6O₂) + O₂ = (O₂⁺ • 7O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.9 ± 0.4	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.9	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Ion clustering data, 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
MM - Michael M. Meot-Ner (Mautner)
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 O₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	12.0697 ± 0.0002	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	101.	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	94.72	kcal/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
0.4480 ± 0.0060	LPES	Ervin, Anusiewicz, et al., 2003	B
0.4510 ± 0.0070	LPES	Travers, Cowles, et al., 1989	B
0.4400 ± 0.0080	LPES	Celotta, Bennett, et al., 1972	89SAW puts DH(H-O2.) at 59 kcal/mol, implying ΔHacid=362.5; B
0.451 ± 0.052	ECD	Chen and Wentworth, 1983	B
0.44 ± 0.10	CIDT	Tiernan and Wu, 1978	From O₂^-; B
0.40 ± 0.10	NBIE	Durup, Parlant, et al., 1977	B
0.450 ± 0.024	ETS	Burrow, 1974	B
0.50 ± 0.10	NBIE	Baeda, 1972	B
0.430 ± 0.030	LPES	Celotta, Bennett, et al., 1971	B
0.460 ± 0.050	NBIE	Nalley and Compton, 1971	B
>0.45 ± 0.10	Endo	Tiernan, Hughes, et al., 1971	B
0.50 ± 0.20	NBIE	Lacmann and Herschbach, 1970	B
0.430 ± 0.020	Kine	Pack and Phelps, 1966	B
>0.479998	Endo	Berkowitz, Chupka, et al., 1971	B
>0.56 ± 0.10	Endo	Chantry, 1971	B
0.725005	ECD	Chen and Chen, 2003	B
>1.27 ± 0.20	Endo	Bailey and Mahadevan, 1970	B
1.119 ± 0.069	IMRB	Vogt, Hauffle, et al., 1970	B
>1.10 ± 0.10	EIAE	Stockdale, Compton, et al., 1969	From NO₂; B
0.150 ± 0.050	PD	Burch, Smith, et al., 1958	B

Proton affinity at 298K

Proton affinity (kcal/mol)	Reference	Comment
100.6 ± 0.8	Litorja and Ruscic, 1998	T = 298K; MM

Ionization energy determinations

IE (eV)	Method	Reference	Comment
12.0697 ± 0.0002	S	Tonkyn, Winniczek, et al., 1989	LL
12.1 ± 0.1	EI	Grade, Wienecke, et al., 1983	LBLHLM
12.8 ± 0.5	EI	Gomez, Chatillon, et al., 1982	LBLHLM
12.0 ± 1.0	S	Farber, Srivastava, et al., 1982	LBLHLM
12.076 ± 0.002	PE	MacNeil and Dixon, 1977	LLK
12.071	PE	Kronebusch and Berkowitz, 1976	LLK
12.071 ± 0.001	PE	Samson and Gardner, 1975	LLK
12.0 ± 0.5	EI	Hildenbrand, 1975	LLK
12.2 ± 0.2	EI	Bennett, Lin, et al., 1974	LLK
12.07 ± 0.01	PI	Tanaka and Tanaka, 1973	LLK
12.08	PE	Natalis, 1973	LLK
12.077	PE	Dromey, Morrison, et al., 1973	LLK
12.127	PE	Vilesov and Lopatin, 1972	LLK
12.072 ± 0.008	PI	Dibeler and Walker, 1967	RDSH
12.059 ± 0.001	S	Samson and Cairns, 1966	RDSH
12.078 ± 0.005	PI	Brehm, 1966	RDSH
12.065 ± 0.003	PI	Nicholson, 1963	RDSH
12.08 ± 0.01	PI	Watanabe, 1957	RDSH
12.30	PE	Kimura, Katsumata, et al., 1981	Vertical value; LLK
12.33 ± 0.01	PE	Banna and Shirley, 1976	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
O⁺	18.734	O	PIPECO	Blyth, Powis, et al., 1981	LLK
O⁺	17.28	O^-	PI	Oertel, Schenk, et al., 1980	LLK
O⁺	18.69 ± 0.04	O	EI	Locht and Schopman, 1974	LLK
O⁺	17.3 ± 0.2	O^-	EI	Locht and Momigny, 1971	LLK
O⁺	17.25 ± 0.01	O^-	PI	Dibeler and Walker, 1967	RDSH
O⁺	17.272 ± 0.024	O^-	PI	Elder, Villarejo, et al., 1965	RDSH
O⁺	18.8 ± 0.4	O	PI	Weissler, Samson, et al., 1959	RDSH
O⁺	18.99 ± 0.05	O	EI	Frost and McDowell, 1959	RDSH

Anion protonation reactions

+ =

By formula: O₂^- + H⁺ = HO₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	352.99 ± 0.72	kcal/mol	D-EA	Travers, Cowles, et al., 1989	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	346.67 ± 0.82	kcal/mol	H-TS	Travers, Cowles, et al., 1989	gas phase; B

Ion clustering data

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

Data compiled as indicated in comments:
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
B - John E. Bartmess

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

+ Oxygen = ( • Oxygen )

By formula: Ca⁺ + O₂ = (Ca⁺ • O₂)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
6.0	296.	FA	Spears and Fehsenfeld, 1972	gas phase; M

HO₂⁺ + Oxygen = (HO₂⁺ • Oxygen )

By formula: HO₂⁺ + O₂ = (HO₂⁺ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	20.0	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	27.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

(HO₂⁺ • Oxygen ) + Oxygen = (HO₂⁺ • 2 Oxygen )

By formula: (HO₂⁺ • O₂) + O₂ = (HO₂⁺ • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.9 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	6.6	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	22.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; M

(HO₂⁺ • 2 Oxygen ) + Oxygen = (HO₂⁺ • 3 Oxygen )

By formula: (HO₂⁺ • 2O₂) + O₂ = (HO₂⁺ • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.7 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	3.2	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.3	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	20.	cal/mol*K	N/A	Hiraoka, Saluja, et al., 1979	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
1.1	105.	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; Entropy change calculated or estimated; M

(HO₂⁺ • 3 Oxygen ) + Oxygen = (HO₂⁺ • 4 Oxygen )

By formula: (HO₂⁺ • 3O₂) + O₂ = (HO₂⁺ • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.5 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 4 Oxygen ) + Oxygen = (HO₂⁺ • 5 Oxygen )

By formula: (HO₂⁺ • 4O₂) + O₂ = (HO₂⁺ • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.2 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.9	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 5 Oxygen ) + Oxygen = (HO₂⁺ • 6 Oxygen )

By formula: (HO₂⁺ • 5O₂) + O₂ = (HO₂⁺ • 6O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.0 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.3	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 6 Oxygen ) + Oxygen = (HO₂⁺ • 7 Oxygen )

By formula: (HO₂⁺ • 6O₂) + O₂ = (HO₂⁺ • 7O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.0 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.5	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 7 Oxygen ) + Oxygen = (HO₂⁺ • 8 Oxygen )

By formula: (HO₂⁺ • 7O₂) + O₂ = (HO₂⁺ • 8O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.8 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(HO₂⁺ • 8 Oxygen ) + Oxygen = (HO₂⁺ • 9 Oxygen )

By formula: (HO₂⁺ • 8O₂) + O₂ = (HO₂⁺ • 9O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.7 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.6	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

H₃⁺ + Oxygen = (H₃⁺ • Oxygen )

By formula: H₃⁺ + O₂ = (H₃⁺ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.5	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.6	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M

(H₃⁺ • Oxygen ) + Oxygen = (H₃⁺ • 2 Oxygen )

By formula: (H₃⁺ • O₂) + O₂ = (H₃⁺ • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.5	kcal/mol	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.	cal/mol*K	PHPMS	Hiraoka, Saluja, et al., 1979	gas phase; From thermochemical cycle(O2H+)O2; M

+ Oxygen = ( • Oxygen )

By formula: Li⁺ + O₂ = (Li⁺ • O₂)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
4.2	319.	DT	Colonna-Romano and Keller, 1976	gas phase; low E/N; M

+ Oxygen = ( • Oxygen )

By formula: NO^- + O₂ = (NO^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.9 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	14.5	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
-0.4	200.	FA	Dunkin, Fehsenfeld, et al., 1971	gas phase; DG>; M

( • Oxygen ) + Oxygen = ( • 2 Oxygen )

By formula: (NO^- • O₂) + O₂ = (NO^- • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.9 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.7	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

( • 2 Oxygen ) + Oxygen = ( • 3 Oxygen )

By formula: (NO^- • 2O₂) + O₂ = (NO^- • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.8 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.7	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

( • 3 Oxygen ) + Oxygen = ( • 4 Oxygen )

By formula: (NO^- • 3O₂) + O₂ = (NO^- • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.1	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

( • 4 Oxygen ) + Oxygen = ( • 5 Oxygen )

By formula: (NO^- • 4O₂) + O₂ = (NO^- • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4 ± 0.2	kcal/mol	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.2	cal/mol*K	PHPMS	Hiraoka and Yamabe, 1991	gas phase; M

+ Oxygen = ( • Oxygen )

By formula: Na⁺ + O₂ = (Na⁺ • O₂)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
0.2	310.	DT	Keller and Beyer, 1971	gas phase; low E/N; M

+ Oxygen = ( • Oxygen )

By formula: O⁺ + O₂ = (O⁺ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	42.9	kcal/mol	PDiss	Hiller and Vestal, 1982	gas phase; M
Δ_rH°	48.	kcal/mol	PI	Linn, Ono, et al., 1981	gas phase; M
Δ_rH°	49.9	kcal/mol	PDiss	Mosely, Ozenne, et al., 1981	gas phase; M

( • Oxygen ) + Oxygen = ( • 2 Oxygen )

By formula: (O⁺ • O₂) + O₂ = (O⁺ • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.9	kcal/mol	PI	Linn, Ono, et al., 1981	gas phase; M

( • 2 Oxygen ) + Oxygen = ( • 3 Oxygen )

By formula: (O⁺ • 2O₂) + O₂ = (O⁺ • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	0.9	kcal/mol	PI	Linn, Ono, et al., 1981	gas phase; M

O^- + Oxygen = (O^- • Oxygen )

By formula: O^- + O₂ = (O^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	32.	kcal/mol	PDiss	Hiller and Vestal, 1981	gas phase; From thermochemical cycle, Δ_rH<; M
Δ_rH°	39.0	kcal/mol	PES	Novich, Engelking, et al., 1979	gas phase; From thermochemical cycle, from EA(O3), D(O-O2) AND EA(O); M
Δ_rH°	38.	kcal/mol	PDiss	Cosby, Moseley, et al., 1978	gas phase; M
Δ_rH°	42.	kcal/mol	CID	Lifschitz, Wu, et al., 1978	gas phase; M

+ Oxygen = ( • Oxygen )

By formula: O₂⁺ + O₂ = (O₂⁺ • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10. ± 1.	kcal/mol	AVG	N/A	Average of 5 out of 6 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.8	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	25.02	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M
Δ_rS°	20.	cal/mol*K	PHPMS	Durden, Kebarle, et al., 1969	gas phase; M
Δ_rS°	20.6	cal/mol*K	PHPMS	Yang and Conway, 1964	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.8	300.	DT	Rakshit and Warneck, 1981	gas phase; M
3.3	300.	DT	Rakshit and Warneck, 1980	gas phase; M
3.4	296.	FA	Howard, Bierbaum, et al., 1972	gas phase; M
5.9	200.	FA	Adams and Bohme, 1970	gas phase; M

( • Oxygen ) + Oxygen = ( • 2 Oxygen )

By formula: (O₂⁺ • O₂) + O₂ = (O₂⁺ • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	5.9 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	6.87 ± 0.06	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	26.3	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	31.78	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

( • 2 Oxygen ) + Oxygen = ( • 3 Oxygen )

By formula: (O₂⁺ • 2O₂) + O₂ = (O₂⁺ • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.5 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	2.5 ± 0.1	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.7	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	19.8	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

( • 3 Oxygen ) + Oxygen = ( • 4 Oxygen )

By formula: (O₂⁺ • 3O₂) + O₂ = (O₂⁺ • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.1 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	2.46 ± 0.18	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.2	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	23.9	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

( • 4 Oxygen ) + Oxygen = ( • 5 Oxygen )

By formula: (O₂⁺ • 4O₂) + O₂ = (O₂⁺ • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.9 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rH°	1.8 ± 0.7	kcal/mol	PHPMS	Conway and Janik, 1970	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	17.0	cal/mol*K	PHPMS	Conway and Janik, 1970	gas phase; M

( • 5 Oxygen ) + Oxygen = ( • 6 Oxygen )

By formula: (O₂⁺ • 5O₂) + O₂ = (O₂⁺ • 6O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.9 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.7	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 6 Oxygen ) + Oxygen = ( • 7 Oxygen )

By formula: (O₂⁺ • 6O₂) + O₂ = (O₂⁺ • 7O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.9 ± 0.4	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.9	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 7 Oxygen ) + Oxygen = ( • 8 Oxygen )

By formula: (O₂⁺ • 7O₂) + O₂ = (O₂⁺ • 8O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.82	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.	cal/mol*K	N/A	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M

+ Oxygen = ( • Oxygen )

By formula: O₂^- + O₂ = (O₂^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12. ± 4.	kcal/mol	AVG	N/A	Average of 5 out of 7 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M
Δ_rS°	32.	cal/mol*K	PHPMS	Conway and Nesbit, 1968	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.2 ± 1.1	kcal/mol	TDAs	Hiraoka, 1888	gas phase; see also Sherwood, Hanold, et al., 1996. Aquino, Taylor, et al., 2001 calns indicate rectangular anion; B
Δ_rG°	5.4 ± 1.0	kcal/mol	IMRE	Payzant J.D. and Kebarle, 1972	gas phase; B
Δ_rG°	3.2 ± 1.0	kcal/mol	IMRE	Pack and Phelps, 1971	gas phase; B
Δ_rG°	4.00 ± 0.50	kcal/mol	IMRE	Parkes, 1971	gas phase; B
Δ_rG°	3.8 ± 1.0	kcal/mol	TDAs	Conway and Nesbit, 1968	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.5	300.	DT	Pack and Phelps, 1971	gas phase; M

( • Oxygen ) + Oxygen = ( • 2 Oxygen )

By formula: (O₂^- • O₂) + O₂ = (O₂^- • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.5 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.9	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 2 Oxygen ) + Oxygen = ( • 3 Oxygen )

By formula: (O₂^- • 2O₂) + O₂ = (O₂^- • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.3	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 3 Oxygen ) + Oxygen = ( • 4 Oxygen )

By formula: (O₂^- • 3O₂) + O₂ = (O₂^- • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.8 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 4 Oxygen ) + Oxygen = ( • 5 Oxygen )

By formula: (O₂^- • 4O₂) + O₂ = (O₂^- • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.5 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.4	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 5 Oxygen ) + Oxygen = ( • 6 Oxygen )

By formula: (O₂^- • 5O₂) + O₂ = (O₂^- • 6O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.5 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.2	cal/mol*K	PHPMS	Hiraoka, 1988	gas phase; M

( • 6 Oxygen ) + Oxygen = ( • 7 Oxygen )

By formula: (O₂^- • 6O₂) + O₂ = (O₂^- • 7O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.40	kcal/mol	PHPMS	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.	cal/mol*K	N/A	Hiraoka, 1988	gas phase; Entropy change calculated or estimated; M

O₃^- + Oxygen = (O₃^- • Oxygen )

By formula: O₃^- + O₂ = (O₃^- • O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.10 ± 0.20	kcal/mol	TDAs	Hiraoka, 1988, 2	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.0	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-3.60 ± 0.50	kcal/mol	TDAs	Hiraoka, 1988, 2	gas phase; B

(O₃^- • Oxygen ) + Oxygen = (O₃^- • 2 Oxygen )

By formula: (O₃^- • O₂) + O₂ = (O₃^- • 2O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.0 ± 0.2	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.4	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

(O₃^- • 2 Oxygen ) + Oxygen = (O₃^- • 3 Oxygen )

By formula: (O₃^- • 2O₂) + O₂ = (O₃^- • 3O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.0 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.0	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

(O₃^- • 3 Oxygen ) + Oxygen = (O₃^- • 4 Oxygen )

By formula: (O₃^- • 3O₂) + O₂ = (O₃^- • 4O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.6 ± 0.3	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.4	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; M

(O₃^- • 4 Oxygen ) + Oxygen = (O₃^- • 5 Oxygen )

By formula: (O₃^- • 4O₂) + O₂ = (O₃^- • 5O₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.54	kcal/mol	PHPMS	Hiraoka, 1988, 2	gas phase; Δ_rH, Δ_rS approximate; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.4	cal/mol*K	PHPMS	Hiraoka, 1988, 2	gas phase; Δ_rH, Δ_rS approximate; M

O₄^- + + Oxygen = N₂O₄^-

By formula: O₄^- + N₂ + O₂ = N₂O₄^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.90 ± 0.20	kcal/mol	TDAs	Hiraoka, 1988, 2	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-2.10 ± 0.50	kcal/mol	TDAs	Hiraoka, 1988, 2	gas phase; B

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, Notes

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Notes

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Symbols used in this document:

AE	Appearance energy
EA	Electron affinity
IE (evaluated)	Recommended ionization energy
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
T	Temperature
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

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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