Sulfur dioxide

Formula: O₂S
Molecular weight: 64.064
IUPAC Standard InChI: InChI=1S/O2S/c1-3-2
IUPAC Standard InChIKey: RAHZWNYVWXNFOC-UHFFFAOYSA-N
CAS Registry Number: 7446-09-5
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript.
Other names: Sulfurous acid anhydride; Fermenicide powder; Fermenticide liquid; Sulfur oxide (SO2); Sulfurous anhydride; Sulfurous oxide; SO2; Sulphur dioxide; Fermenicide liquid; Schwefeldioxyd; Siarki dwutlenek; Sulfur oxide; UN 1079; Sulfur dioxide (SO2); Sulfur superoxide
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Information on this page:
Other data available:
- Reaction thermochemistry data: reactions 51 to 100, reactions 101 to 102
- Henry's Law data
- Mass spectrum (electron ionization)
- Gas Chromatography
- Fluid Properties
Data at other public NIST sites:
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Gas phase thermochemistry data

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

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	-70.939 ± 0.048	kcal/mol	Review	Cox, Wagman, et al., 1984	CODATA Review value
Δ_fH°_gas	-70.946	kcal/mol	Review	Chase, 1998	Data last reviewed in June, 1961
Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	59.327 ± 0.012	cal/mol*K	Review	Cox, Wagman, et al., 1984	CODATA Review value
S°_{gas,1 bar}	59.324	cal/mol*K	Review	Chase, 1998	Data last reviewed in June, 1961

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)	298. to 1200.	1200. to 6000.
A	5.122011	13.73850
B	17.77030	0.241235
C	-13.80310	-0.018234
D	3.909021	0.001237
E	0.020729	-0.966874
F	-73.08050	-77.53681
G	60.91950	72.36611
H	-70.94699	-70.94699
Reference	Chase, 1998	Chase, 1998
Comment	Data last reviewed in June, 1961	Data last reviewed in June, 1961

Phase change data

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

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos

Quantity	Value	Units	Method	Reference	Comment
T_fus	200.75	K	N/A	Hoffman and Vanderwerf, 1946	Uncertainty assigned by TRC = 0.5 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_triple	197.64	K	N/A	Giauque and Stephenson, 1938	Uncertainty assigned by TRC = 0.05 K; Temp. Scale based on T0 = 273.10 K; TRC
Quantity	Value	Units	Method	Reference	Comment
P_triple	0.0165	atm	N/A	Giauque and Stephenson, 1938	Uncertainty assigned by TRC = 0.000066 atm; TRC
Quantity	Value	Units	Method	Reference	Comment
T_c	430.34	K	N/A	Travers and Usher, 1906	Uncertainty assigned by TRC = 0.4 K; TRC

Enthalpy of vaporization

Δ_vapH (kcal/mol)	Temperature (K)	Method	Reference	Comment
5.95	263.	N/A	Giauque and Stephenson, 1938, 2	Based on data from 200. to 263. K.; AC
5.95	263.	C	Giauque and Stephenson, 1938, 2	AC

Antoine Equation Parameters

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

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Temperature (K)	A	B	C	Reference	Comment
177.7 to 263.	3.48015	668.225	-72.252	Stull, 1947	Coefficents calculated by NIST from author's data.
263. to 414.9	4.37227	966.575	-42.071	Stull, 1947	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, Gas phase ion energetics data, Ion clustering data, IR Spectrum, References, Notes

Data compiled as indicated in comments:
B - John E. Bartmess
M - 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. 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

+ Sulfur dioxide = ( • )

By formula: Cl^- + O₂S = (Cl^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22.2 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B,M
Δ_rH°	20.9 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1985	gas phase; B
Δ_rH°	22.2 ± 2.2	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..Cl^- in Keesee, Lee, et al., 1980; B,M
Δ_rH°	21.80 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	20.9	kcal/mol	ICR	Larson and McMahon, 1984	gas phase; switching reaction(Cl-)t-C4H9OH, Entropy change calculated or estimated; French, Ikuta, et al., 1982; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.6	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Δ_rS°	24.1	cal/mol*K	N/A	Bohringer, Fahey, et al., 1984	gas phase; switching reaction(Cl-)H2O), Entropy change calculated or estimated; Keesee and Castleman, 1980; M
Δ_rS°	20.8	cal/mol*K	N/A	Larson and McMahon, 1984	gas phase; switching reaction(Cl-)t-C4H9OH, Entropy change calculated or estimated; French, Ikuta, et al., 1982; M
Δ_rS°	23.2	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	15.7 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B
Δ_rG°	14.7 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1985	gas phase; B
Δ_rG°	15.0 ± 1.6	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..Cl^- in Keesee, Lee, et al., 1980; B,M
Δ_rG°	14.80 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B
Δ_rG°	14.7	kcal/mol	ICR	Larson and McMahon, 1984	gas phase; switching reaction(Cl-)t-C4H9OH, Entropy change calculated or estimated; French, Ikuta, et al., 1982; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
14.2	296.	FA	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(Cl-)H2O; M

+ Sulfur dioxide = ( • )

By formula: F^- + O₂S = (F^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	53.8 ± 2.2	kcal/mol	CIDT	Lobring, Check, et al., 2003	gas phase; B
Δ_rH°	53.0 ± 2.5	kcal/mol	CIDT	Squires, 1992	gas phase; B
Δ_rH°	43.8	kcal/mol	ICR	Larson and McMahon, 1985	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Δ_rH°	43.8 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1983	gas phase; These relative affinities are ca. 10 kcal/mol weaker than threshold values (see Wenthold and Squires, 1995) for donors greater than ca. 27 kcal/mol in free energy. This discrepancy has not yet been resolved, though the stronger value appears preferable.; B,M
Δ_rH°	59.	kcal/mol	SAMS	Robbiani and Franklin, 1979	gas phase; Cl- + CO2ClF --> SO2F- + Cl2, Δ_rH>; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.	cal/mol*K	N/A	Larson and McMahon, 1985	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Δ_rS°	23.0	cal/mol*K	N/A	Larson and McMahon, 1983	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	36.6	kcal/mol	ICR	Larson and McMahon, 1985	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Δ_rG°	36.9 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1983	gas phase; These relative affinities are ca. 10 kcal/mol weaker than threshold values (see Wenthold and Squires, 1995) for donors greater than ca. 27 kcal/mol in free energy. This discrepancy has not yet been resolved, though the stronger value appears preferable.; B,M

+ Sulfur dioxide = ( • )

By formula: NO₃^- + O₂S = (NO₃^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	17.2 ± 2.0	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..NO₃^-, Keesee, Lee, et al., 1980; B,M
Δ_rH°	18.2 ± 1.2	kcal/mol	TDAs	Wlodek, Luczynski, et al., 1983	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	25.2	cal/mol*K	N/A	Bohringer, Fahey, et al., 1984	gas phase; switching reaction(NO3-)H2O, Entropy change calculated or estimated; Lee, Keesee, et al., 1980; M
Δ_rS°	31.6	cal/mol*K	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	9.6 ± 2.0	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..NO₃^-, Keesee, Lee, et al., 1980; B,M
Δ_rG°	10.00 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B
Δ_rG°	8.80 ± 0.90	kcal/mol	TDAs	Wlodek, Luczynski, et al., 1983	gas phase; B
Δ_rG°	10.6	kcal/mol	FA	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(NO3-)SO2, Entropy change calculated or estimated; Lee, Keesee, et al., 1980; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
10.0	299.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

+ Sulfur dioxide = ( • )

By formula: I^- + O₂S = (I^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.3 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B,M
Δ_rH°	12.90 ± 0.10	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.6	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Δ_rS°	20.2	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	9.0 ± 2.6	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B
Δ_rG°	1.70 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B
Δ_rG°	6.80 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
9.0	301.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

O₂S^- + Sulfur dioxide = (O₂S^- • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	24.00 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	21.3 ± 1.3	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Δ_rH°	18.50	kcal/mol	N/A	Dresch, Kramer, et al., 1991	gas phase; Both dissociation and electron detachment?; B
Δ_rH°	18.30	kcal/mol	N/A	Snodgrass, Coe, et al., 1988	gas phase; Appears to be dissociation + electron detachment; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	33.8	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	13.90 ± 0.40	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B
Δ_rG°	10.4 ± 2.2	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

+ Sulfur dioxide = ( • )

By formula: NO₂^- + O₂S = (NO₂^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	25.90 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	24.3 ± 1.0	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..NO₂^-, Keesee, Lee, et al., 1980; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	36.8	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Δ_rS°	31.6	cal/mol*K	N/A	Bohringer, Fahey, et al., 1984	gas phase; switching reaction(NO2-)H2O, Entropy change calculated or estimated; Lee, Keesee, et al., 1980; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	14.90 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

CO₃^- + Sulfur dioxide = (CO₃^- • )

By formula: CO₃^- + O₂S = (CO₃^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.	kcal/mol	HPMS	Keesee, Lee, et al., 1980	gas phase; switching reaction(O-)CO2, Entropy change calculated or estimated; Fehsenfeld and Ferguson, 1974; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.	cal/mol*K	N/A	Keesee, Lee, et al., 1980	gas phase; switching reaction(O-)CO2, Entropy change calculated or estimated; Fehsenfeld and Ferguson, 1974; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
8.0	296.	HPMS	Keesee, Lee, et al., 1980	gas phase; switching reaction(O-)CO2, Entropy change calculated or estimated; Fehsenfeld and Ferguson, 1974; M

( • Sulfur dioxide ) + = ( • • )

By formula: (Cl^- • O₂S) + H₂O = (Cl^- • H₂O • O₂S)

Bond type: Hydrogen bond (negative ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.40	kcal/mol	TDAs	Upschulte, Schelling, et al., 1984	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.4	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	4.60	kcal/mol	TDAs	Upschulte, Schelling, et al., 1984	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
5.5	296.	FA	Fehsenfeld and Ferguson, 1974	gas phase; From thermochemical cycle,switching reaction(H2O/SO2); M

( • Sulfur dioxide ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.3 ± 1.0	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	12.3	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.2	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Δ_rS°	22.7	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	5.5 ± 2.2	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • Sulfur dioxide ) + = ( • 2)

By formula: (NO₂^- • O₂S) + O₂S = (NO₂^- • 2O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.00 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	9.8	kcal/mol	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.5	cal/mol*K	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; M
Δ_rS°	16.8	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	4.00 ± 0.40	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • 3 Sulfur dioxide ) + = ( • 4)

By formula: (Na⁺ • 3O₂S) + O₂S = (Na⁺ • 4O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.3	kcal/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	27.	cal/mol*K	N/A	Castleman, Peterson, et al., 1983	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.2	328.	HPMS	Castleman, Peterson, et al., 1983	gas phase; Entropy change calculated or estimated; M

( • Sulfur dioxide ) + = ( • • )

By formula: (Br^- • O₂S) + HBr = (Br^- • HBr • O₂S)

Bond type: Hydrogen bond (negative ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.2	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; From thermochemical cycle,switching reaction(Br- HBr)SO2; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.2	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; From thermochemical cycle,switching reaction(Br- HBr)SO2; M

( • Sulfur dioxide • ) + = ( • 2 • )

By formula: (Cl^- • O₂S • H₂O) + O₂S = (Cl^- • 2O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.8	kcal/mol	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	26.0	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
4.1	296.	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

+ Sulfur dioxide = ( • )

By formula: Na⁺ + O₂S = (Na⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	18.9	kcal/mol	FA	Perry, Rowe, et al., 1980	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.3	cal/mol*K	N/A	Perry, Rowe, et al., 1980	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	12.8	kcal/mol	FA	Perry, Rowe, et al., 1980	gas phase; Entropy change calculated or estimated; M

( • Sulfur dioxide ) + = ( • • )

By formula: (Br^- • O₂S) + HCl = (Br^- • HCl • O₂S)

Bond type: Hydrogen bond (negative ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22.4	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; From thermochemical cycle,switching reaction(Br-)SO2; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.6	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; From thermochemical cycle,switching reaction(Br-)SO2; M

( • 2) + Sulfur dioxide = ( • • 2)

By formula: (Cl^- • 2H₂O) + O₂S = (Cl^- • O₂S • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.1	kcal/mol	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.4	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
8.4	296.	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

(O₂S^- • Sulfur dioxide ) + = (O₂S^- • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.10 ± 0.30	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Δ_rH°	8.3	kcal/mol	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.0	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.90 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

( • • Sulfur dioxide ) + = ( • 2 • )

By formula: (Cl^- • H₂O • O₂S) + H₂O = (Cl^- • 2H₂O • O₂S)

Bond type: Hydrogen bond (negative ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.30	kcal/mol	TDAs	Upschulte, Schelling, et al., 1984	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.7	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.40	kcal/mol	TDAs	Upschulte, Schelling, et al., 1984	gas phase; B

( • 2 Sulfur dioxide ) + = ( • • 2)

By formula: (Cl^- • 2O₂S) + H₂O = (Cl^- • H₂O • 2O₂S)

Bond type: Hydrogen bond (negative ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.90	kcal/mol	TDAs	Upschulte, Schelling, et al., 1984	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.7	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.10	kcal/mol	TDAs	Upschulte, Schelling, et al., 1984	gas phase; B

( • 2 Sulfur dioxide ) + = ( • 3)

By formula: (NO₂^- • 2O₂S) + O₂S = (NO₂^- • 3O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.60 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	13.4	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	2.60 ± 0.80	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • Sulfur dioxide ) + = ( • • )

By formula: (Cl^- • O₂S) + HCl = (Cl^- • HCl • O₂S)

Bond type: Hydrogen bond (negative ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.9	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; From thermochemical cycle; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.2	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; From thermochemical cycle; M

( • ) + Sulfur dioxide = ( • • )

By formula: (Cl^- • H₂O) + O₂S = (Cl^- • O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	17.4	kcal/mol	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.2	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
11.5	296.	HPMS	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(Cl- H2O)H2O; M

HO₂S⁺ + Sulfur dioxide = (HO₂S⁺ • )

By formula: HO₂S⁺ + O₂S = (HO₂S⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	21.3	kcal/mol	PHPMS	Szulejko and McMahon, 1992	gas phase; M
Δ_rH°	23.2	kcal/mol	PHPMS	McMahon and Kebarle, 1986	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	25.7	cal/mol*K	PHPMS	Szulejko and McMahon, 1992	gas phase; M
Δ_rS°	27.4	cal/mol*K	PHPMS	McMahon and Kebarle, 1986	gas phase; M

( • 2 Sulfur dioxide ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.00 ± 0.10	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.1	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.10 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • 2 Sulfur dioxide ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.20 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.7	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.80 ± 0.60	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • Sulfur dioxide ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.10 ± 0.10	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.6	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.60 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • 3 Sulfur dioxide ) + = ( • 4)

By formula: (Cl^- • 3O₂S) + O₂S = (Cl^- • 4O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.60 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.2	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.6 ± 1.0	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • Sulfur dioxide ) + = ( • • )

By formula: (I^- • O₂S) + H₂O = (I^- • H₂O • O₂S)

Bond type: Hydrogen bond (negative ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.50 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.5	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

HO^- + Sulfur dioxide = (HO^- • )

By formula: HO^- + O₂S = (HO^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	61.9 ± 2.8	kcal/mol	CIDT	Squires, 1992	gas phase; Dissociative protonation between HCl, MeCHClCO2H; B
Δ_rH°	>50.9 ± 3.0	kcal/mol	IMRB	Hierl and Paulson, 1984	gas phase; CO₂..HO^- + SO₂ ->. data revised per 92SQU; B

+ Sulfur dioxide = ( • )

By formula: Br^- + O₂S = (Br^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	19.3 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.0	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	12.7 ± 2.6	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B

CN^- + Sulfur dioxide = (CN^- • )

By formula: CN^- + O₂S = (CN^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	21.70 ± 0.80	kcal/mol	TDAs	Larson, Szulejko, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	28.	cal/mol*K	PHPMS	Larson, Szulejko, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	13.40 ± 0.20	kcal/mol	TDAs	Larson, Szulejko, et al., 1988	gas phase; B

+ Sulfur dioxide = ( • )

By formula: Cs⁺ + O₂S = (Cs⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.8	kcal/mol	DT	McKnight and Sawina, 1972	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.9	cal/mol*K	DT	McKnight and Sawina, 1972	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
5.2	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • Sulfur dioxide ) + = ( • • )

By formula: (NO₂^- • O₂S) + C₂H₅NO₃ = (NO₂^- • C₂H₅NO₃ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.4	kcal/mol	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	10.4	cal/mol*K	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; Entropy change is questionable; M

( • 2 • Sulfur dioxide ) + = ( • 3 • )

By formula: (H₄N⁺ • 2H₂O • O₂S) + H₂O = (H₄N⁺ • 3H₂O • O₂S)

Bond type: Hydrogen bond (positive ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	5.2	kcal/mol	HPMS	Banic and Iribarne, 1985	gas phase; From thermochemical cycle,switching reaction, electric fields; M

( • Sulfur dioxide ) + = ( • 2)

By formula: (NO₃^- • O₂S) + O₂S = (NO₃^- • 2O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.8	kcal/mol	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	14.1	cal/mol*K	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; Entropy change is questionable; M

( • • Sulfur dioxide ) + = ( • 2 • )

By formula: (H₄N⁺ • H₂O • O₂S) + H₂O = (H₄N⁺ • 2H₂O • O₂S)

Bond type: Hydrogen bond (positive ion to hydride)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	7.4	kcal/mol	HPMS	Banic and Iribarne, 1985	gas phase; From thermochemical cycle,switching reaction, electric fields; M

(O₂S^- • 2 • 3 Sulfur dioxide ) + = (O₂S^- • 3 • 3)

By formula: (O₂S^- • 2H₂O • 3O₂S) + H₂O = (O₂S^- • 3H₂O • 3O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.60 ± 0.30	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.00 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • 2 • 4 Sulfur dioxide ) + = (O₂S^- • 3 • 4)

By formula: (O₂S^- • 2H₂O • 4O₂S) + H₂O = (O₂S^- • 3H₂O • 4O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.10 ± 0.70	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	2.60 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • 5 Sulfur dioxide • 2) + = (O₂S^- • 6 • 2)

By formula: (O₂S^- • 5O₂S • 2H₂O) + O₂S = (O₂S^- • 6O₂S • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.80 ± 0.90	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.10 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • 6 Sulfur dioxide • 2) + = (O₂S^- • 7 • 2)

By formula: (O₂S^- • 6O₂S • 2H₂O) + O₂S = (O₂S^- • 7O₂S • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.70 ± 0.70	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.60 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • • 3 Sulfur dioxide ) + = (O₂S^- • 2 • 3)

By formula: (O₂S^- • H₂O • 3O₂S) + H₂O = (O₂S^- • 2H₂O • 3O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.10 ± 0.40	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.80 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • • 4 Sulfur dioxide ) + = (O₂S^- • 2 • 4)

By formula: (O₂S^- • H₂O • 4O₂S) + H₂O = (O₂S^- • 2H₂O • 4O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.10 ± 0.70	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.00 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

( • 4) + Sulfur dioxide = ( • • 4)

By formula: (H₃O⁺ • 4H₂O) + O₂S = (H₃O⁺ • O₂S • 4H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
2.6	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M
2.6	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

(O₂S^- • 6 Sulfur dioxide • ) + = (O₂S^- • 7 • )

By formula: (O₂S^- • 6O₂S • H₂O) + O₂S = (O₂S^- • 7O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.20 ± 0.60	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.70 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

( • Sulfur dioxide ) + = ( • • )

By formula: (NO₃^- • O₂S) + H₂O = (NO₃^- • H₂O • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	4.30 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
4.3	299.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • ) + Sulfur dioxide = ( • • )

By formula: (I^- • H₂O) + O₂S = (I^- • O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	9.00 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
7.1	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

(O₂S^- • 2 Sulfur dioxide • ) + = (O₂S^- • 3 • )

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^- • Sulfur dioxide • ) + = (O₂S^- • 2 • )

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^- • Sulfur dioxide • ) + = (O₃S^- • 2 • )

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

+ Sulfur dioxide = ( • )

By formula: CH₃⁺ + O₂S = (CH₃⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	60.6	kcal/mol	PHPMS	McMahon, Heinis, et al., 1988	gas phase; switching reaction(CH3+)N2, Entropy change calculated or estimated, uses MCA(N2) = 48.3 kcal/mol; Foster, Williamson, et al., 1974; M

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Ion clustering data, IR Spectrum, 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:
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
B - John E. Bartmess

View reactions leading to O₂S⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	12.349 ± 0.001	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	160.7	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	153.8	kcal/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.1070 ± 0.0080	LPES	Nimlos and Ellison, 1986	B
1.097 ± 0.036	LPES	Celotta, Bennett, et al., 1974	B
1.10 ± 0.10	TDEq	Chowdhury, Heinis, et al., 1986	ΔGea(423 K) = -26.1 kcal/mol; ΔSea (estimated) = +2.0 eu. Original: Caldwell and Kebarle, 19842. Not direct measurement, but anchor for extensiveEA equilibrium scale. See text.; B
1.10 ± 0.20	IMRB	Grabowski, VanDoren, et al., 1984	B
1.04998	Endo	Refaey and Franklin, 1976	B
1.00 ± 0.10	Endo	Hughes, Lifschitz, et al., 1973	B
1.00 ± 0.050	PD	Feldman, 1970	B
1.06 ± 0.10	IMRB	Kraus, Muller-Duysing, et al., 1961	Between NH₂^-, C^-; B
1.14 ± 0.15	NBIE	Rothe, Tang, et al., 1975	B

Gas basicity at 298K

Gas basicity (review) (kcal/mol)	Reference	Comment
<149.	Milligan, Fairley, et al., 1998	Irreversible PT from SO2H+ to C2N2 shows GB(SO2) < GB(C2N2), and using GB(C2N2) for reference from this paper; MM
<145.	Milligan, Fairley, et al., 1998	Irreversible PT from SO2H+ to C2H2 shows GB(SO2) < (GB(C2H2) + 4.5 kcal/mol); MM

Ionization energy determinations

IE (eV)	Method	Reference	Comment
12.5 ± 0.1	EI	Snow and Thomas, 1990	LL
12.3494 ± 0.0002	PE	Wang, Lee, et al., 1987	LBLHLM
12.5 ± 0.3	EI	Orient and Srivastava, 1984	LBLHLM
12.4 ± 0.2	EI	Smith and Stevenson, 1981	LLK
12.3	PE	Lloyd and Roberts, 1973	LLK
12.31	PE	Bock, Solouki, et al., 1973	LLK
12.30 ± 0.01	PE	Eland and Danby, 1968	RDSH
12.32 ± 0.01	PI	Dibeler and Liston, 1968	RDSH
12.34	S	Golomb, Watanabe, et al., 1962	RDSH
12.34 ± 0.02	PI	Watanabe, 1957	RDSH
12.50	PE	Kimura, Katsumata, et al., 1981	Vertical value; LLK
12.54	PE	Kroner, Strack, et al., 1973	Vertical value; LLK
12.50	PE	Chadwick, Frost, et al., 1973	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
O⁺	23.5 ± 0.5	SO	EI	Orient and Srivastava, 1984	LBLHLM
O⁺	20.6	SO	EI	Reese, Dibeter, et al., 1958	RDSH
OS⁺	16.5 ± 0.5	O	EI	Orient and Srivastava, 1984	LBLHLM
OS⁺	16.2 ± 0.2	O	EI	Smith and Stevenson, 1981	LLK
OS⁺	15.930 ± 0.005	O	PE	Weiss, Hsieh, et al., 1979	LLK
SO⁺	15.81 ± 0.02	O	PI	Dibeler and Liston, 1968	RDSH
O₂⁺	17.5 ± 0.3	S	EI	Reese, Dibeter, et al., 1958	RDSH
S⁺	16.5 ± 0.5	O₂/2O	EI	Orient and Srivastava, 1984	LBLHLM
S⁺	22.	2O	EI	Smith and Stevenson, 1981	LLK
S⁺	16.334	O₂/2O	PE	Weiss, Hsieh, et al., 1979	LLK
S⁺	17.5 ± 0.3	O₂	EI	Reese, Dibeter, et al., 1958	RDSH

Ion clustering data

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, 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

( • ) + Sulfur dioxide = ( • • )

By formula: (Br^- • HBr) + O₂S = (Br^- • O₂S • HBr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.9	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.9	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M

( • ) + Sulfur dioxide = ( • • )

By formula: (Br^- • HCl) + O₂S = (Br^- • O₂S • HCl)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.1	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.6	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M

+ Sulfur dioxide = ( • )

By formula: Br^- + O₂S = (Br^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	19.3 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.0	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	12.7 ± 2.6	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B

( • Sulfur dioxide ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.2	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.7	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M

( • 2 Sulfur dioxide ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.5	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	13.8	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M

+ Sulfur dioxide = ( • )

By formula: CH₃⁺ + O₂S = (CH₃⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	60.6	kcal/mol	PHPMS	McMahon, Heinis, et al., 1988	gas phase; switching reaction(CH3+)N2, Entropy change calculated or estimated, uses MCA(N2) = 48.3 kcal/mol; Foster, Williamson, et al., 1974; M

CN^- + Sulfur dioxide = (CN^- • )

By formula: CN^- + O₂S = (CN^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	21.70 ± 0.80	kcal/mol	TDAs	Larson, Szulejko, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	28.	cal/mol*K	PHPMS	Larson, Szulejko, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	13.40 ± 0.20	kcal/mol	TDAs	Larson, Szulejko, et al., 1988	gas phase; B

CO₃^- + Sulfur dioxide = (CO₃^- • )

By formula: CO₃^- + O₂S = (CO₃^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.	kcal/mol	HPMS	Keesee, Lee, et al., 1980	gas phase; switching reaction(O-)CO2, Entropy change calculated or estimated; Fehsenfeld and Ferguson, 1974; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.	cal/mol*K	N/A	Keesee, Lee, et al., 1980	gas phase; switching reaction(O-)CO2, Entropy change calculated or estimated; Fehsenfeld and Ferguson, 1974; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
8.0	296.	HPMS	Keesee, Lee, et al., 1980	gas phase; switching reaction(O-)CO2, Entropy change calculated or estimated; Fehsenfeld and Ferguson, 1974; M

C₄H₆⁺ + Sulfur dioxide = (C₄H₆⁺ • )

By formula: C₄H₆⁺ + O₂S = (C₄H₆⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.7	kcal/mol	PI	Grover, Walters, et al., 1985	gas phase; M

C₄H₈⁺ + Sulfur dioxide = (C₄H₈⁺ • )

By formula: C₄H₈⁺ + O₂S = (C₄H₈⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4	kcal/mol	PI	Grover, Walters, et al., 1985	gas phase; M

C₄H₈⁺ + Sulfur dioxide = (C₄H₈⁺ • )

By formula: C₄H₈⁺ + O₂S = (C₄H₈⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.4	kcal/mol	PI	Grover, Walters, et al., 1985	gas phase; M

( • ) + Sulfur dioxide = ( • • )

By formula: (Cl^- • HCl) + O₂S = (Cl^- • O₂S • HCl)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.3	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.5	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M

( • ) + Sulfur dioxide = ( • • )

By formula: (Cl^- • H₂O) + O₂S = (Cl^- • O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	17.4	kcal/mol	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.2	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
11.5	296.	HPMS	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(Cl- H2O)H2O; M

( • 2) + Sulfur dioxide = ( • • 2)

By formula: (Cl^- • 2H₂O) + O₂S = (Cl^- • O₂S • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.1	kcal/mol	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.4	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
8.4	296.	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

+ Sulfur dioxide = ( • )

By formula: Cl^- + O₂S = (Cl^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22.2 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B,M
Δ_rH°	20.9 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1985	gas phase; B
Δ_rH°	22.2 ± 2.2	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..Cl^- in Keesee, Lee, et al., 1980; B,M
Δ_rH°	21.80 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	20.9	kcal/mol	ICR	Larson and McMahon, 1984	gas phase; switching reaction(Cl-)t-C4H9OH, Entropy change calculated or estimated; French, Ikuta, et al., 1982; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.6	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Δ_rS°	24.1	cal/mol*K	N/A	Bohringer, Fahey, et al., 1984	gas phase; switching reaction(Cl-)H2O), Entropy change calculated or estimated; Keesee and Castleman, 1980; M
Δ_rS°	20.8	cal/mol*K	N/A	Larson and McMahon, 1984	gas phase; switching reaction(Cl-)t-C4H9OH, Entropy change calculated or estimated; French, Ikuta, et al., 1982; M
Δ_rS°	23.2	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	15.7 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B
Δ_rG°	14.7 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1985	gas phase; B
Δ_rG°	15.0 ± 1.6	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..Cl^- in Keesee, Lee, et al., 1980; B,M
Δ_rG°	14.80 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B
Δ_rG°	14.7	kcal/mol	ICR	Larson and McMahon, 1984	gas phase; switching reaction(Cl-)t-C4H9OH, Entropy change calculated or estimated; French, Ikuta, et al., 1982; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
14.2	296.	FA	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(Cl-)H2O; M

( • Sulfur dioxide • ) + = ( • 2 • )

By formula: (Cl^- • O₂S • H₂O) + O₂S = (Cl^- • 2O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.8	kcal/mol	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	26.0	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
4.1	296.	HPMS	Upschulte, Schelling, et al., 1984	gas phase; From thermochemical cycle; M

( • Sulfur dioxide ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.3 ± 1.0	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	12.3	kcal/mol	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.2	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Δ_rS°	22.7	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	5.5 ± 2.2	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • 2 Sulfur dioxide ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.00 ± 0.10	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.1	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.10 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • 3 Sulfur dioxide ) + = ( • 4)

By formula: (Cl^- • 3O₂S) + O₂S = (Cl^- • 4O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.60 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.2	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.6 ± 1.0	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

ClO₄^- + Sulfur dioxide = (ClO₄^- • )

By formula: ClO₄^- + O₂S = (ClO₄^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	5.70 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
5.7	290.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • ) + Sulfur dioxide = ( • • )

By formula: (Cs⁺ • H₂O) + O₂S = (Cs⁺ • O₂S • H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
4.3	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • 2) + Sulfur dioxide = ( • • 2)

By formula: (Cs⁺ • 2H₂O) + O₂S = (Cs⁺ • O₂S • 2H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.5	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

+ Sulfur dioxide = ( • )

By formula: Cs⁺ + O₂S = (Cs⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.8	kcal/mol	DT	McKnight and Sawina, 1972	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.9	cal/mol*K	DT	McKnight and Sawina, 1972	gas phase; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
5.2	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

+ Sulfur dioxide = ( • )

By formula: F^- + O₂S = (F^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	53.8 ± 2.2	kcal/mol	CIDT	Lobring, Check, et al., 2003	gas phase; B
Δ_rH°	53.0 ± 2.5	kcal/mol	CIDT	Squires, 1992	gas phase; B
Δ_rH°	43.8	kcal/mol	ICR	Larson and McMahon, 1985	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Δ_rH°	43.8 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1983	gas phase; These relative affinities are ca. 10 kcal/mol weaker than threshold values (see Wenthold and Squires, 1995) for donors greater than ca. 27 kcal/mol in free energy. This discrepancy has not yet been resolved, though the stronger value appears preferable.; B,M
Δ_rH°	59.	kcal/mol	SAMS	Robbiani and Franklin, 1979	gas phase; Cl- + CO2ClF --> SO2F- + Cl2, Δ_rH>; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.	cal/mol*K	N/A	Larson and McMahon, 1985	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Δ_rS°	23.0	cal/mol*K	N/A	Larson and McMahon, 1983	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	36.6	kcal/mol	ICR	Larson and McMahon, 1985	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Δ_rG°	36.9 ± 2.0	kcal/mol	IMRE	Larson and McMahon, 1983	gas phase; These relative affinities are ca. 10 kcal/mol weaker than threshold values (see Wenthold and Squires, 1995) for donors greater than ca. 27 kcal/mol in free energy. This discrepancy has not yet been resolved, though the stronger value appears preferable.; B,M

+ Sulfur dioxide = ( • )

By formula: H^- + O₂S = (H^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	63. ± 16.	kcal/mol	IMRB	Sheldon, Currie, et al., 1985	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	57. ± 16.	kcal/mol	IMRB	Sheldon, Currie, et al., 1985	gas phase; B

HO^- + Sulfur dioxide = (HO^- • )

By formula: HO^- + O₂S = (HO^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	61.9 ± 2.8	kcal/mol	CIDT	Squires, 1992	gas phase; Dissociative protonation between HCl, MeCHClCO2H; B
Δ_rH°	>50.9 ± 3.0	kcal/mol	IMRB	Hierl and Paulson, 1984	gas phase; CO₂..HO^- + SO₂ ->. data revised per 92SQU; B

HO₂S⁺ + Sulfur dioxide = (HO₂S⁺ • )

By formula: HO₂S⁺ + O₂S = (HO₂S⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	21.3	kcal/mol	PHPMS	Szulejko and McMahon, 1992	gas phase; M
Δ_rH°	23.2	kcal/mol	PHPMS	McMahon and Kebarle, 1986	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	25.7	cal/mol*K	PHPMS	Szulejko and McMahon, 1992	gas phase; M
Δ_rS°	27.4	cal/mol*K	PHPMS	McMahon and Kebarle, 1986	gas phase; M

HO₄S^- + Sulfur dioxide = (HO₄S^- • )

By formula: HO₄S^- + O₂S = (HO₄S^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.7	kcal/mol	HPMS	Keesee and Castleman, 1986	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	26.1	cal/mol*K	HPMS	Keesee and Castleman, 1986	gas phase; M

( • 3) + Sulfur dioxide = ( • • 3)

By formula: (H₃O⁺ • 3H₂O) + O₂S = (H₃O⁺ • O₂S • 3H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
4.2	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • 4) + Sulfur dioxide = ( • • 4)

By formula: (H₃O⁺ • 4H₂O) + O₂S = (H₃O⁺ • O₂S • 4H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
2.6	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M
2.6	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

+ Sulfur dioxide = ( • )

By formula: H₃O⁺ + O₂S = (H₃O⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22.0	kcal/mol	PHPMS	Szulejko and McMahon, 1992	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.7	cal/mol*K	PHPMS	Szulejko and McMahon, 1992	gas phase; M

( • ) + Sulfur dioxide = ( • • )

By formula: (H₄N⁺ • H₂O) + O₂S = (H₄N⁺ • O₂S • H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
6.4	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • 2) + Sulfur dioxide = ( • • 2)

By formula: (H₄N⁺ • 2H₂O) + O₂S = (H₄N⁺ • O₂S • 2H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
5.0	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • 3) + Sulfur dioxide = ( • • 3)

By formula: (H₄N⁺ • 3H₂O) + O₂S = (H₄N⁺ • O₂S • 3H₂O)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.6	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • ) + Sulfur dioxide = ( • • )

By formula: (I^- • H₂O) + O₂S = (I^- • O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	9.00 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
7.1	300.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

+ Sulfur dioxide = ( • )

By formula: I^- + O₂S = (I^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.3 ± 2.0	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B,M
Δ_rH°	12.90 ± 0.10	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.6	cal/mol*K	PHPMS	Caldwell and Kebarle, 1985	gas phase; M
Δ_rS°	20.2	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	9.0 ± 2.6	kcal/mol	TDAs	Caldwell and Kebarle, 1985	gas phase; B
Δ_rG°	1.70 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B
Δ_rG°	6.80 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
9.0	301.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • Sulfur dioxide • ) + = ( • 2 • )

By formula: (I^- • O₂S • H₂O) + O₂S = (I^- • 2O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	7.10 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B

( • Sulfur dioxide ) + = ( • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.10 ± 0.10	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.6	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.60 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • 2 Sulfur dioxide ) + = ( • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.20 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.7	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.80 ± 0.60	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

+ Sulfur dioxide = ( • )

By formula: NO^- + O₂S = (NO^- • O₂S)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
7.8	296.	SAMS	Vanderhoff and Heimerl, 1977	gas phase; switching reaction(NO+)NO; Puckett and Teague, 1971; M

+ Sulfur dioxide = ( • )

By formula: NO₂^- + O₂S = (NO₂^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	25.90 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	24.3 ± 1.0	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..NO₂^-, Keesee, Lee, et al., 1980; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	36.8	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Δ_rS°	31.6	cal/mol*K	N/A	Bohringer, Fahey, et al., 1984	gas phase; switching reaction(NO2-)H2O, Entropy change calculated or estimated; Lee, Keesee, et al., 1980; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	14.90 ± 0.30	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • Sulfur dioxide ) + = ( • 2)

By formula: (NO₂^- • O₂S) + O₂S = (NO₂^- • 2O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.00 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	9.8	kcal/mol	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.5	cal/mol*K	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; M
Δ_rS°	16.8	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	4.00 ± 0.40	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • 2 Sulfur dioxide ) + = ( • 3)

By formula: (NO₂^- • 2O₂S) + O₂S = (NO₂^- • 3O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.60 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	13.4	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	2.60 ± 0.80	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

( • ) + Sulfur dioxide = ( • • )

By formula: (NO₃^- • H₂O) + O₂S = (NO₃^- • O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	7.2	kcal/mol	HPMS	Banic and Iribarne, 1985	gas phase; From thermochemical cycle,switching reaction, electric fields; M

+ Sulfur dioxide = ( • )

By formula: NO₃^- + O₂S = (NO₃^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	17.2 ± 2.0	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..NO₃^-, Keesee, Lee, et al., 1980; B,M
Δ_rH°	18.2 ± 1.2	kcal/mol	TDAs	Wlodek, Luczynski, et al., 1983	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	25.2	cal/mol*K	N/A	Bohringer, Fahey, et al., 1984	gas phase; switching reaction(NO3-)H2O, Entropy change calculated or estimated; Lee, Keesee, et al., 1980; M
Δ_rS°	31.6	cal/mol*K	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	9.6 ± 2.0	kcal/mol	TDEq	Bohringer, Fahey, et al., 1984	gas phase; Relative to HOH..NO₃^-, Keesee, Lee, et al., 1980; B,M
Δ_rG°	10.00 ± 0.10	kcal/mol	TDAs	Banic and Iribarne, 1985	gas phase; B
Δ_rG°	8.80 ± 0.90	kcal/mol	TDAs	Wlodek, Luczynski, et al., 1983	gas phase; B
Δ_rG°	10.6	kcal/mol	FA	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(NO3-)SO2, Entropy change calculated or estimated; Lee, Keesee, et al., 1980; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
10.0	299.	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

( • Sulfur dioxide ) + = ( • 2)

By formula: (NO₃^- • O₂S) + O₂S = (NO₃^- • 2O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.8	kcal/mol	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	14.1	cal/mol*K	HPMS	Wlodek, Luczynski, et al., 1983	gas phase; Entropy change is questionable; M

( • ) + Sulfur dioxide = ( • • )

By formula: (Na⁺ • H₂O) + O₂S = (Na⁺ • O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.1	kcal/mol	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.4	cal/mol*K	HPMS	Upschulte, Schelling, et al., 1984	gas phase; M

( • 3) + Sulfur dioxide = ( • • 3)

By formula: (Na⁺ • 3H₂O) + O₂S = (Na⁺ • O₂S • 3H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	4.8	kcal/mol	HPMS	Banic and Iribarne, 1985	gas phase; electric fields; M

+ Sulfur dioxide = ( • )

By formula: Na⁺ + O₂S = (Na⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	18.9	kcal/mol	FA	Perry, Rowe, et al., 1980	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.3	cal/mol*K	N/A	Perry, Rowe, et al., 1980	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	12.8	kcal/mol	FA	Perry, Rowe, et al., 1980	gas phase; Entropy change calculated or estimated; M

( • Sulfur dioxide ) + = ( • 2)

By formula: (Na⁺ • O₂S) + O₂S = (Na⁺ • 2O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	16.6	kcal/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	25.5	cal/mol*K	HPMS	Castleman, Peterson, et al., 1983	gas phase; M

( • 2 Sulfur dioxide ) + = ( • 3)

By formula: (Na⁺ • 2O₂S) + O₂S = (Na⁺ • 3O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.3	kcal/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	26.9	cal/mol*K	HPMS	Castleman, Peterson, et al., 1983	gas phase; M

( • 3 Sulfur dioxide ) + = ( • 4)

By formula: (Na⁺ • 3O₂S) + O₂S = (Na⁺ • 4O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.3	kcal/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	27.	cal/mol*K	N/A	Castleman, Peterson, et al., 1983	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
3.2	328.	HPMS	Castleman, Peterson, et al., 1983	gas phase; Entropy change calculated or estimated; M

O^- + Sulfur dioxide = (O^- • )

By formula: O^- + O₂S = (O^- • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	60.	kcal/mol	FA	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(O-)CO2, Δ_rH>; Hiller and Vestal, 1980, Keesee and Castleman, 1986; M

(O^- • Sulfur dioxide ) + = (O^- • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.3	kcal/mol	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.9	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M

OS⁺ + Sulfur dioxide = (OS⁺ • )

By formula: OS⁺ + O₂S = (OS⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.8	kcal/mol	PI	Erickson and Ng, 1981	gas phase; M

+ Sulfur dioxide = ( • )

By formula: O₂⁺ + O₂S = (O₂⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	9.6	kcal/mol	FA	Adams and Bohme, 1970	gas phase; switching reaction(O2+)O2; Conway and Janik, 1970; M

O₂S⁺ + Sulfur dioxide = (O₂S⁺ • )

By formula: O₂S⁺ + O₂S = (O₂S⁺ • O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	15.2	kcal/mol	PI	Erickson and Ng, 1981	gas phase; M

O₂S^- + Sulfur dioxide = (O₂S^- • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	24.00 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B,M
Δ_rH°	21.3 ± 1.3	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Δ_rH°	18.50	kcal/mol	N/A	Dresch, Kramer, et al., 1991	gas phase; Both dissociation and electron detachment?; B
Δ_rH°	18.30	kcal/mol	N/A	Snodgrass, Coe, et al., 1988	gas phase; Appears to be dissociation + electron detachment; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	33.8	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	13.90 ± 0.40	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B
Δ_rG°	10.4 ± 2.2	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • 5 Sulfur dioxide • 2) + = (O₂S^- • 6 • 2)

By formula: (O₂S^- • 5O₂S • 2H₂O) + O₂S = (O₂S^- • 6O₂S • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.80 ± 0.90	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.10 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • 6 Sulfur dioxide • ) + = (O₂S^- • 7 • )

By formula: (O₂S^- • 6O₂S • H₂O) + O₂S = (O₂S^- • 7O₂S • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.20 ± 0.60	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.70 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • 6 Sulfur dioxide • 2) + = (O₂S^- • 7 • 2)

By formula: (O₂S^- • 6O₂S • 2H₂O) + O₂S = (O₂S^- • 7O₂S • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.70 ± 0.70	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.60 ± 0.20	kcal/mol	TDAs	Vacher, Leduc, et al., 1994	gas phase; B

(O₂S^- • Sulfur dioxide ) + = (O₂S^- • 2)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.10 ± 0.30	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Δ_rH°	8.3	kcal/mol	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.0	cal/mol*K	HPMS	Keesee, Lee, et al., 1980	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.90 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 2 Sulfur dioxide ) + = (O₂S^- • 3)

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.40 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	3.00 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 3 Sulfur dioxide ) + = (O₂S^- • 4)

By formula: (O₂S^- • 3O₂S) + O₂S = (O₂S^- • 4O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	5.40 ± 0.30	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	2.20 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 4 Sulfur dioxide ) + = (O₂S^- • 5)

By formula: (O₂S^- • 4O₂S) + O₂S = (O₂S^- • 5O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.20 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.20 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 5 Sulfur dioxide ) + = (O₂S^- • 6)

By formula: (O₂S^- • 5O₂S) + O₂S = (O₂S^- • 6O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.60 ± 0.30	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.90 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 6 Sulfur dioxide ) + = (O₂S^- • 7)

By formula: (O₂S^- • 6O₂S) + O₂S = (O₂S^- • 7O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.40 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.50 ± 0.20	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 7 Sulfur dioxide ) + = (O₂S^- • 8)

By formula: (O₂S^- • 7O₂S) + O₂S = (O₂S^- • 8O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.40 ± 0.30	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.3 ± 1.2	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 8 Sulfur dioxide ) + = (O₂S^- • 9)

By formula: (O₂S^- • 8O₂S) + O₂S = (O₂S^- • 9O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.00 ± 0.40	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.3 ± 1.5	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • 9 Sulfur dioxide ) + = (O₂S^- • 10)

By formula: (O₂S^- • 9O₂S) + O₂S = (O₂S^- • 10O₂S)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.00 ± 0.60	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.1 ± 2.3	kcal/mol	TDAs	Vacher, Jorda, et al., 1992	gas phase; B

(O₂S^- • Sulfur dioxide • ) + = (O₂S^- • 2 • )

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

(O₂S^- • 2 Sulfur dioxide • ) + = (O₂S^- • 3 • )

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^- • ) + Sulfur dioxide = (O₂S^- • • )

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

O₃S^- + Sulfur dioxide = (O₃S^- • )

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.30 ± 0.10	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	7.60 ± 0.20	kcal/mol	TDAs	Keesee, Lee, et al., 1980	gas phase; B

(O₃S^- • Sulfur dioxide • ) + = (O₃S^- • 2 • )

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

(O₃S^- • ) + Sulfur dioxide = (O₃S^- • • )

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

O₄S^- + Sulfur dioxide = (O₄S^- • )

By formula: O₄S^- + O₂S = (O₄S^- • O₂S)

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
6.7	296.	FA	Fehsenfeld and Ferguson, 1974	gas phase; switching reaction(SO4-)H2O; M

IR Spectrum

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

Data compiled by: Coblentz Society, Inc.

Data compiled by: Pamela M. Chu, Franklin R. Guenther, George C. Rhoderick, and Walter J. Lafferty

gas; IFS66V (Bruker); 3-Term B-H Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); Boxcar Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); Happ Genzel Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); NB Strong Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); Triangular Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, 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]

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

Hoffman and Vanderwerf, 1946
Hoffman, K.R.; Vanderwerf, C.A., Addition Compounds of Sulfur Dioxide with Pyridine and the Picolines, J. Am. Chem. Soc., 1946, 68, 997. [all data]

Giauque and Stephenson, 1938
Giauque, W.F.; Stephenson, C.C., Sulfur Dioxide. The Heat Capacity of Solid and Liquid. Vapor Pressure. Heat of Vap. The Entropy Values from Termal and Molecular Data, J. Am. Chem. Soc., 1938, 60, 1389. [all data]

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Travers, M.W.; Usher, F.L., The behavior of certain substance at the critical point, Z. Phys. Chem., Stoechiom. Verwandtschaftsl., 1906, 57, 365-81. [all data]

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Giauque, W.F.; Stephenson, C.C., Sulfur Dioxide. The Heat Capacity of Solid and Liquid. Vapor Pressure. Heat of Vaporization. The Entropy Values from Thermal and Molecular Data, J. Am. Chem. Soc., 1938, 60, 6, 1389-1394, https://doi.org/10.1021/ja01273a034 . [all data]

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Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

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Caldwell, G.; Kebarle, P., The hydrogen bond energies of the bihalide ions XHX- and YHX-, Can. J. Chem., 1985, 63, 1399. [all data]

Larson and McMahon, 1985
Larson, J.W.; McMahon, T.B., Fluoride and chloride affinities of the main group oxides, fluorides, oxofluorides, and alkyls. Quantitative scales of lewis acidities from ICR halide exchange equilibria, J. Am. Chem. Soc., 1985, 107, 766. [all data]

Bohringer, Fahey, et al., 1984
Bohringer, H.; Fahey, D.W.; Fehsenfeld, F.C.; Ferguson, E.E., Bond energies of the molecules H₂O, SO₂, H₂O₂, and HCl to various atmospheric negative ions, J. Chem. Phys., 1984, 81, 2805. [all data]

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Keesee, R.G.; Lee, N.; Castleman, A.W., Jr., Properties of clusters in the gas phase: V. Complexes of neutral molecules onto negative ions, J. Chem. Phys., 1980, 73, 2195. [all data]

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Larson, J.W.; McMahon, T.B., Gas phase negative ion chemistry of alkylchloroformates, Can. J. Chem., 1984, 62, 675. [all data]

French, Ikuta, et al., 1982
French, M.A.; Ikuta, S.; Kebarle, P., Hydrogen bonding of O-H and C-H hydrogen donors to Cl^-. Results from mass spectrometric measurement of the ion-molecule equilibria RH + Cl^- = RHCl^-, Can. J. Chem., 1982, 60, 1907. [all data]

Keesee and Castleman, 1980
Keesee, R.G.; Castleman, A.W., Jr., Gas phase studies of hydration complexes of Cl- and I- and comparison to electrostatic calculations in the gas phase, Chem. Phys. Lett., 1980, 74, 139. [all data]

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Fehsenfeld, F.C.; Ferguson, E.E., Laboratory studies of negative ion reactions with atmospheric trace constituents, J. Chem. Phys., 1974, 61, 3181. [all data]

Lobring, Check, et al., 2003
Lobring, K.C.; Check, C.E.; Sunderlin, L.S., The fluoride affinity of SO2, Int. J. Mass Spectrom., 2003, 222, 1-3, 221-227, https://doi.org/10.1016/S1387-3806(02)00950-8 . [all data]

Squires, 1992
Squires, R.R., Gas Phase Thermochemical Properties of the Bicarbonate and Bisulfate Ions, Int. J. Mass Spectrom. Ion Proc., 1992, 117, 565, https://doi.org/10.1016/0168-1176(92)80114-G . [all data]

Arshadi, Yamdagni, et al., 1970
Arshadi, M.; Yamdagni, R.; Kebarle, P., Hydration of Halide Negative Ions in the Gas Phase. II. Comparison of Hydration Energies for the Alkali Positive and Halide Negative Ions, J. Phys. Chem., 1970, 74, 7, 1475, https://doi.org/10.1021/j100702a014 . [all data]

Larson and McMahon, 1983
Larson, J.W.; McMahon, T.B., Strong hydrogen bonding in gas-phase anions. An ion cyclotron resonance determination of fluoride binding energetics to bronsted acids from gas-phase fluoride exchange equilibria measurements, J. Am. Chem. Soc., 1983, 105, 2944. [all data]

Wenthold and Squires, 1995
Wenthold, P.G.; Squires, R.R., Bond dissociation energies of F2(-) and HF2(-). A gas-phase experimental and G2 theoretical study, J. Phys. Chem., 1995, 99, 7, 2002, https://doi.org/10.1021/j100007a034 . [all data]

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Wlodek, Luczynski, et al., 1983
Wlodek, S.; Luczynski, Z.; Wincel, H., Gas phase complexes of NO₂^- and NO₃^- with SO₂, Int. J. Mass Spectrom. Ion Processes, 1983, 49, 301. [all data]

Lee, Keesee, et al., 1980
Lee, N.; Keesee, R.G.; Castleman, A.W., Jr., The properties of clusters in the gas phase. IV. Complexes of H₂O and HNO_x clustering on NO_x-, J. Chem. Phys., 1980, 72, 1089. [all data]

Banic and Iribarne, 1985
Banic, C.M.; Iribarne, J.V., Equilibrium Constants for Clustering of Neutral Molecules about Gaseous Ions, J. Chem. Phys., 1985, 83, 12, 6432, https://doi.org/10.1063/1.449543 . [all data]

Vacher, Leduc, et al., 1994
Vacher, J.R.; Leduc, E.; Fitaire, M., Stabilities of Anionic Mixed Clusters of Sulfur Dioxide and Water, Int. J. Mass Spectrom. Ion Proc., 1994, 135, 2-3, 139, https://doi.org/10.1016/0168-1176(94)03985-2 . [all data]

Dresch, Kramer, et al., 1991
Dresch, T.; Kramer, H.; Thurner, Y.; Weber, R., Photoelectrons from Negative Dimers and Clusters of Sulfur Dioxide, Chem. Phys. Lett., 1991, 177, 4-5, 383, https://doi.org/10.1016/0009-2614(91)85070-D . [all data]

Snodgrass, Coe, et al., 1988
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Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, References

Symbols used in this document:

AE	Appearance energy
EA	Electron affinity
IE (evaluated)	Recommended ionization energy
P_triple	Triple point pressure
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
T	Temperature
T_c	Critical temperature
T_fus	Fusion (melting) point
T_triple	Triple point temperature
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
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
Δ_vapH	Enthalpy of vaporization

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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