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 1 to 50, reactions 51 to 100, reactions 101 to 102
- Ion clustering data
- IR Spectrum
- Mass spectrum (electron ionization)
- Gas Chromatography
- Fluid Properties
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Gas phase thermochemistry data

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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

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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:

Henry's Law data

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Data compiled by: Rolf Sander

Henry's Law constant (water solution)

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

k°_H (mol/(kg*bar))	d(ln(k_H))/d(1/T) (K)	Method	Reference	Comment
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, Henry's Law data, References, Notes

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
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

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, 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]

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]

Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Henry's Law data, Gas phase ion energetics data, 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_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_vapH	Enthalpy of vaporization

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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