Sulfurous acid
Names | |
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IUPAC name
Sulfurous acid
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Other names
Sulfuric(IV) acid
Thionic acid Sulfinic acid | |
Identifiers | |
3D model (
JSmol ) |
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ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard
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100.029.066 |
EC Number |
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1458 | |
KEGG | |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
H2SO3 | |
Molar mass | 82.07 g/mol |
Acidity (pKa) | 1.857, 7.172 |
Conjugate base
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Bisulfite |
Hazards | |
GHS labelling: | |
Danger | |
H314, H332 | |
P260, P261, P264, P271, P280, P301+P330+P331, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P363, P405, P501 | |
Flash point | Non-flammable |
Safety data sheet (SDS) | ICSC 0074 |
Related compounds | |
Related compounds
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Sulfur dioxide Sulfuric acid Selenous acid |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sulfuric(IV) acid (United Kingdom spelling: sulphuric(IV) acid), also known as sulfurous (UK: sulphurous) acid and thionic acid,[citation needed] is the chemical compound with the formula H2SO3.
Raman spectra of solutions of sulfur dioxide in water show only signals due to the SO2 molecule and the bisulfite ion, HSO−3.[1] The intensities of the signals are consistent with the following equilibrium:
17O
Attempts to concentrate the solutions of sulfurous acid simply reverses the equilibrium, producing sulfur dioxide and water vapor. A
History and production
Sulfurous acid is commonly known to not exist in its free state, and due to this, it is stated in textbooks that it cannot be isolated in the water-free form.[3] However, the molecule has been detected in the gas phase in 1988 by the dissociative ionization of diethyl sulfite.[4] The conjugate bases of this elusive acid are, however, common anions, bisulfite (or hydrogen sulfite) and sulfite. Sulfurous acid is an intermediate species in the formation of acid rain from sulfur dioxide.[5]
Uses
Aqueous solutions of sulfur dioxide, which sometimes are referred to as sulfurous acid, are used as
See also
References
- ISBN 0-07-032768-8
- ISBN 978-0-13-175553-6.
- ISBN 978-0-08-037941-8.
- .
- ISBN 0-7167-1806-5.
- ^ L. Kolditz, Anorganische Chemie, VEB Deutscher Verlag der Wissenschaften, Berlin 1983, S. 476.