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
Permanent link for this species. Use this link for bookmarking this species for future reference.
Information on this page:
Other data available:
- Reaction thermochemistry data: reactions 51 to 100, reactions 101 to 102
Options:
- Switch to SI units

Data at NIST subscription sites:

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.

Gas phase thermochemistry data

Go To: Top, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, 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.

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

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, Henry's Law data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, 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)

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

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, Henry's Law data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, 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

Henry's Law data

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, References, Notes

Data compiled by: Rolf Sander

Henry's Law constant (water solution)

k_H(T) = k°_H exp(d(ln(k_H))/d(1/T) ((1/T) - 1/(298.15 K)))
k°_H = Henry's law constant for solubility in water at 298.15 K (mol/(kg*bar))
d(ln(k_H))/d(1/T) = Temperature dependence constant (K)

k°_H (mol/(kg*bar))	d(ln(k_H))/d(1/T) (K)	Method	Reference	Comment
1.4	2900.	L	N/A
1.5	3200.	Q	N/A	Only the tabulated data between T = 273. K and T = 303. K from missing citation was used to derive k_H and -Δ k_H/R. Above T = 303. K the tabulated data could not be parameterized by equation (reference missing) very well. The partial pressure of water vapor (needed to convert some Henry's law constants) was calculated using the formula given by missing citation. The quantities A and α from missing citation were assumed to be identical.
1.2	3100.	C	N/A
1.2	3200.	C	N/A
1.2	3100.	T	N/A
1.2	3100.	Q	N/A	missing citation refer to several references in their list of Henry's law constants but they don't assign them to specific species.
1.3	3100.	N/A	N/A
1.2	3200.	X	N/A	The value is taken from the compilation of solubilities by W. Asman (unpublished).
1.2		X	N/A	Value given here as quoted by missing citation.
1.2		C	N/A
1.3	2800.	X	N/A
1.2	3000.	L	N/A
1.4	2800.	L	N/A
1.2	3100.	X	N/A	The value is taken from the compilation of solubilities by W. Asman (unpublished).
1.1		c	N/A
1.2	3100.	c	N/A
1.2	3200.	X	N/A	The value is taken from the compilation of solubilities by W. Asman (unpublished).

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Ion clustering data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, 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, Henry's Law data, Gas phase ion energetics data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, 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, Henry's Law data, Gas phase ion energetics data, Ion clustering data, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, 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

Mass spectrum (electron ionization)

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Gas Chromatography, Site Links, NIST Free Links, References, Notes

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

Spectrum

Notice: This spectrum may be better viewed with a Javascript and HTML 5 enabled browser.

Additional Data

View image of digitized spectrum (can be printed in landscape orientation).

Due to licensing restrictions, this spectrum cannot be downloaded.

Owner	NIST Mass Spectrometry Data Center Collection (C) 2014 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.
NIST MS number	191

All mass spectra in this site (plus many more) are available from the NIST/EPA/NIH Mass Spectral Library. Please see the following for information about the library and its accompanying search program.

Gas Chromatography

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

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

Van Den Dool and Kratz RI, polar column, temperature ramp

View large format table.

Column type	Active phase	I	Reference	Comment
Capillary	CP-Wax 52CB	856.	Mahadevan and Farmer, 2006	60. C @ 5. min, 4. K/min, 220. C @ 30. min; Column length: 50. m; Column diameter: 0.32 mm

Normal alkane RI, polar column, temperature ramp

View large format table.

Column type	Active phase	I	Reference	Comment
Capillary	DB-Wax	882.	Chyau and Mau, 1999	60. m/0.25 mm/0.25 μm, N2, 3. K/min; T_start: 40. C; T_end: 210. C

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, Notes

Cox, Wagman, et al., 1984
Cox, J.D.; Wagman, D.D.; Medvedev, V.A., CODATA Key Values for Thermodynamics, Hemisphere Publishing Corp., New York, 1984, 1. [all data]

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

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]

Travers and Usher, 1906
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]

Giauque and Stephenson, 1938, 2
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]

Stull, 1947
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]

Caldwell and Kebarle, 1985
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]

Keesee, Lee, et al., 1980
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]

Larson and McMahon, 1984
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]

Fehsenfeld and Ferguson, 1974
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]

Robbiani and Franklin, 1979
Robbiani, R.; Franklin, J.L., Negative ion-molecule reaction in sulfuryl halides, J. Am. Chem. Soc., 1979, 101, 3709. [all data]

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
Snodgrass, J.T.; Coe, J.V.; Friedhoff, C.B.; McHugh, K.M.; Bowen, K.H., On the Photodissociation of (SO₂)₂^-, J. Chem. Phys., 1988, 88, 12, 8014, https://doi.org/10.1063/1.454261 . [all data]

Upschulte, Schelling, et al., 1984
Upschulte, B.L.; Schelling, F.J.; Keesee, R.G.; Castleman, A.W., Thermochemical Properties of Gas Phase Mixed Clusters: Water and Sulfur Dioxide with Na+ and Cl-, Chem. Phys. Lett., 1984, 111, 4-5, 389, https://doi.org/10.1016/0009-2614(84)85526-8 . [all data]

Castleman, Peterson, et al., 1983
Castleman, A.W.; Peterson, K.I.; Upschulte, B.L.; Schelling, F.J., Energetics and Structure of Na+ Cluster Ions, Int. J. Mass Spectrom. Ion Phys., 1983, 47, 203, https://doi.org/10.1016/0020-7381(83)87171-X . [all data]

Perry, Rowe, et al., 1980
Perry, R.A.; Rowe, B.R.; Viggiano, A.A.; Albritton, D.L.; Ferguson, E.E.; Fehsenfeld, F.C., Laboratory Measurements of Stratospheric Sodium Ion Measurements, Geophys. Res. Lett., 1980, 7, 9, 693, https://doi.org/10.1029/GL007i009p00693 . [all data]

Vacher, Jorda, et al., 1992
Vacher, J.R.; Jorda, M.; Leduc, E.; Fitaire, M., A Determination of the Stabilities of Negative Ion Clusters in SO2 and SO2-O2 Mixtures, Int. J. Mass Spectrom. Ion Proc., 1992, 114, 3, 149, https://doi.org/10.1016/0168-1176(92)80033-W . [all data]

Szulejko and McMahon, 1992
Szulejko, J.; McMahon, T.B., personal communication, 1992. [all data]

McMahon and Kebarle, 1986
McMahon, T.B.; Kebarle, P., Strong hydrogen bonding in gas-phase ions: A high pressure mass spectrometric study of formation and energetics of methyl fluoride proton bound dimer, J. Am. Chem. Soc., 1986, 108, 6502. [all data]

Hierl and Paulson, 1984
Hierl, P.M.; Paulson, J.F., Translational energy dependence of cross sections for reactions of OH^- (H₂O)n with CO₂ and SO₂, J. Chem. Phys., 1984, 80, 4890. [all data]

Larson, Szulejko, et al., 1988
Larson, J.W.; Szulejko, J.E.; McMahon, T.B., Gas Phase Lewis Acid-Base Interactions. An Experimental Determination of Cyanide Binding Energies From Ion Cyclotron Resonance and High-Pressure Mass Spectrometric Equilibrium Measurements., J. Am. Chem. Soc., 1988, 110, 23, 7604, https://doi.org/10.1021/ja00231a004 . [all data]

McKnight and Sawina, 1972
McKnight, L.G.; Sawina, J.M., Drift Velocities and Interactions of Cs+ Ions with Atmospheric Gases, J. Chem. Phys., 1972, 57, 12, 5156, https://doi.org/10.1063/1.1678205 . [all data]

McMahon, Heinis, et al., 1988
McMahon, T.; Heinis, T.; Nicol, G.; Hovey, J.K.; Kebarle, P., Methyl Cation Affinities, J. Am. Chem. Soc., 1988, 110, 23, 7591, https://doi.org/10.1021/ja00231a002 . [all data]

Foster, Williamson, et al., 1974
Foster, M.S.; Williamson, A.D.; Beauchamp, J.L., Photoionization mass spectrometry of trans-azomethane, Int. J. Mass Spectrom. Ion Phys., 1974, 15, 429. [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Nimlos and Ellison, 1986
Nimlos, M.R.; Ellison, G.B., Photoelectron spectroscopy of SO₂^-, S₃^-, and S₂O^-, J. Phys. Chem., 1986, 90, 2574. [all data]

Celotta, Bennett, et al., 1974
Celotta, R.S.; Bennett, R.A.; Hall, J.L., Laser Photodetachment Determination of the Electron Affinities of OH, NH₂, NH, SO₂, and S₂, J. Chem. Phys., 1974, 60, 5, 1740, https://doi.org/10.1063/1.1681268 . [all data]

Chowdhury, Heinis, et al., 1986
Chowdhury, S.; Heinis, T.; Grimsrud, E.P.; Kebarle, P., Entropy Changes and Electron Affinities from Gas-Phase Electron Transfer Equilibria: A^- + B = A + B^-, J. Phys. Chem., 1986, 90, 12, 2747, https://doi.org/10.1021/j100403a037 . [all data]

Caldwell and Kebarle, 1984
Caldwell, G.; Kebarle, P., Binding energies and structural effects in halide anion-ROH and -RCOOH complexes from gas phase equilibria measurements, J. Am. Chem. Soc., 1984, 106, 967. [all data]

Grabowski, VanDoren, et al., 1984
Grabowski, J.J.; VanDoren, J.M.; DePuy, C.H.; Bierbaum, V.M., Flowing Afterglow Studies of the Electron Affinity of SO₂, J. Chem. Phys., 1984, 80, 1, 575, https://doi.org/10.1063/1.446412 . [all data]

Refaey and Franklin, 1976
Refaey, K.M.A.; Franklin, J.L., Endoergic ion-molecule-collision processes of negative ions. I. Collision of I- on SO₂, J. Chem. Phys., 1976, 65, 1994. [all data]

Hughes, Lifschitz, et al., 1973
Hughes, B.M.; Lifschitz, C.; Tiernan, T.O., Electron affinities from endothermic negative-ion charge-transfer reactions. III. NO, NO₂, S₂, CS₂, Cl₂, Br₂, I₂, and C₂H, J. Chem. Phys., 1973, 59, 3162. [all data]

Feldman, 1970
Feldman, D., Photoablosung von Elektronen bei einigen Stabilen Negativen Ionen, Z. Naturfor., 1970, 25A, 621. [all data]

Kraus, Muller-Duysing, et al., 1961
Kraus, K.; Muller-Duysing, W.; Neuert, H., Uber Stosse Langsamer Negativer Ionen mit Ladungsubertragung, Z. Naturfor., 1961, 16A, 1385. [all data]

Rothe, Tang, et al., 1975
Rothe, E.W.; Tang, S.Y.; Reck, G.P., Measurement of electron affinities of O₃, SO₂, and SO₃ by collisional ionization, J. Chem. Phys., 1975, 62, 3829. [all data]

Milligan, Fairley, et al., 1998
Milligan, D.B.; Fairley, D.A.; Meot-Ner (Mautner), M.; McEwan, M.J., Proton affinity of cyanogen and association reactions of C2N2H+ and C2N2CH3+, Int. J. Mass Spectrom., 1998, 180, 285. [all data]

Snow and Thomas, 1990
Snow, K.B.; Thomas, T.F., Mass spectrum, ionization potential, and appearance potentials for fragment ions of sulfuric acid vapor, Int. J. Mass Spectrom. Ion Processes, 1990, 96, 49. [all data]

Wang, Lee, et al., 1987
Wang, L.; Lee, Y.T.; Shirley, D.A., Molecular beam photoelectron spectroscopy of SO₂: Geometry, spectroscopy, and dynamics of SO₂, J. Chem. Phys., 1987, 87, 2489. [all data]

Orient and Srivastava, 1984
Orient, O.J.; Srivastava, S.K., Mass spectrometric determination of partial and total electron impact ionization cross sections of SO₂ from threshold up to 200 eV, J. Chem. Phys., 1984, 80, 140. [all data]

Smith and Stevenson, 1981
Smith, O.I.; Stevenson, J.S., Determination of cross sections for formation of parent and fragment ions by electron impact from SO₂ and SO₃, J. Chem. Phys., 1981, 74, 6777. [all data]

Lloyd and Roberts, 1973
Lloyd, D.R.; Roberts, P.J., The assignment of the photoelectron spectrum of sulphur dioxide, Mol. Phys., 1973, 26, 225. [all data]

Bock, Solouki, et al., 1973
Bock, H.; Solouki, B.; Rosmus, P.; Steudel, R., Photoelectron spectra and molecular properties: SSO and OSO, Angew. Chem. Int. Ed. Engl., 1973, 12, 933. [all data]

Eland and Danby, 1968
Eland, J.H.D.; Danby, C.J., Photoelectron spectra and ionic structure of carbon dioxide, carbon disulphide and sulphur dioxide, Intern. J. Mass Spectrom. Ion Phys., 1968, 1, 111. [all data]

Dibeler and Liston, 1968
Dibeler, V.H.; Liston, S.K., Mass-spectrometric study of photoionization. XI.Hydrogen sulfide and sulfur dioxide, J. Chem. Phys., 1968, 49, 482. [all data]

Golomb, Watanabe, et al., 1962
Golomb, D.; Watanabe, K.; Marmo, F.F., Absorption coefficients of sulfur dioxide in the vacuum ultraviolet, J. Chem. Phys., 1962, 36, 958. [all data]

Watanabe, 1957
Watanabe, K., Ionization potentials of some molecules, J. Chem. Phys., 1957, 26, 542. [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Kroner, Strack, et al., 1973
Kroner, J.; Strack, W.; Holsboer, F.; Kosbahn, W., Zur elektronenstruktur der thiokumulene, Z. Naturforsch. B:, 1973, 28, 188. [all data]

Chadwick, Frost, et al., 1973
Chadwick, D.; Frost, D.C.; Herring, F.G.; Katrib, A.; McDowell, C.A.; McLean, R.A.N., Photoelectron spectra of sulfuryl and thionyl halides, Can. J. Chem., 1973, 51, 1893. [all data]

Reese, Dibeter, et al., 1958
Reese, R.M.; Dibeter, V.H.; Franklin, J.L., Electron impact studies of sulfur dioxide and sulfuryl fluoride, J. Chem. Phys., 1958, 29, 880. [all data]

Weiss, Hsieh, et al., 1979
Weiss, M.J.; Hsieh, T.-C.; Meisels, G.G., Fragmentation of SO₂⁺ prepared in state selected vibrational levels, J. Chem. Phys., 1979, 71, 567. [all data]

Grover, Walters, et al., 1985
Grover, J.R.; Walters, E.A.; Newman, J.K.; White, M.G., Measurement of the Dissociation Energies of Gas - Phase Neutral Dimers by a Photoionization Technique: Values for trans - 2 - Butene/Sulfur Dioxide , (trans - 2 - Butene)2, and Benzene/Sulfur Dioxide, J. Am. Chem. Soc., 1985, 107, 25, 7329, https://doi.org/10.1021/ja00311a020 . [all data]

Sheldon, Currie, et al., 1985
Sheldon, J.C.; Currie, G.J.; Lahnstein, J.; Hayes, R.N.; Bowie, J.H., Gas Phase Ion Chemistry of Ambident Nucleophiles. Reactions of Alkoxide and Thiomethoxide Negative Ions with Hydrogen Free Molecules., Nouv. J. Chem., 1985, 9, 205. [all data]

Keesee and Castleman, 1986
Keesee, R.G.; Castleman, A.W., Jr., Thermochemical data on Ggs-phase ion-molecule association and clustering reactions, J. Phys. Chem. Ref. Data, 1986, 15, 1011. [all data]

Vanderhoff and Heimerl, 1977
Vanderhoff, J.A.; Heimerl, J.M., The Equilibrium Constant for NO+(NO) ---> NO+(SO2) and the Rate Coefficient of SO2 Clustering to NO+, at 296 K, J. Chem. Phys., 1977, 66, 8, 3838, https://doi.org/10.1063/1.434380 . [all data]

Puckett and Teague, 1971
Puckett, L.J.; Teague, M.W., Ion-Molecule Reactions in NO - NH3 Gas Mixtures, J. Chem. Phys., 1971, 54, 11, 4860, https://doi.org/10.1063/1.1674763 . [all data]

Hiller and Vestal, 1980
Hiller, J.F.; Vestal, M.L., Tandem quadrupole study of laser photodissociation of CO₃-, J. Chem. Phys., 1980, 72, 4713. [all data]

Erickson and Ng, 1981
Erickson, J.; Ng, C.Y., Molecular Beam Photoionization Study of SO2 and (SO2)2, J. Chem. Phys., 1981, 75, 4, 1650, https://doi.org/10.1063/1.442242 . [all data]

Adams and Bohme, 1970
Adams, N.G.; Bohme, D., Flowing Afterglow Studies of Formation and Reactions of Cluster Ions of O₂⁺, O₂^-, and O^-, J. Chem. Phys., 1970, 52, 6, 3133, https://doi.org/10.1063/1.1673449 . [all data]

Conway and Janik, 1970
Conway, D.C.; Janik, G.S., Determination of the Bond Energies for the Series O2 - O2+ through O2 - O10+, J. Chem. Phys., 1970, 53, 5, 1859, https://doi.org/10.1063/1.1674262 . [all data]

Mahadevan and Farmer, 2006
Mahadevan, K.; Farmer, L., Key Odor Impact Compounds in Three Yeast Extract Pastes, J. Agric. Food Chem., 2006, 54, 19, 7242-7250, https://doi.org/10.1021/jf061102x . [all data]

Chyau and Mau, 1999
Chyau, C.-C.; Mau, J.-L., Release of volatile compounds from microwave heating of garlic juice with 2,4-decadienals, Food Chem., 1999, 64, 4, 531-535, https://doi.org/10.1016/S0308-8146(98)00162-9 . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Mass spectrum (electron ionization), Gas Chromatography, Site Links, NIST Free Links, 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
d(ln(k_H))/d(1/T)	Temperature dependence parameter for Henry's Law constant
k°_H	Henry's Law constant at 298.15K
Δ_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
The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
Customer support for NIST Standard Reference Data products.

Sulfur dioxide

Data at NIST subscription sites:

Gas phase thermochemistry data

Gas Phase Heat Capacity (Shomate Equation)

Phase change data

Enthalpy of vaporization

Antoine Equation Parameters

Reaction thermochemistry data

Reactions 1 to 50

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Henry's Law data

Henry's Law constant (water solution)

Gas phase ion energetics data

Electron affinity determinations

Gas basicity at 298K

Ionization energy determinations

Appearance energy determinations

Ion clustering data

Clustering reactions

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

IR Spectrum

Mass spectrum (electron ionization)

Spectrum

Help

Credits

Additional Data

Gas Chromatography

Van Den Dool and Kratz RI, polar column, temperature ramp

Normal alkane RI, polar column, temperature ramp

References

Notes