Sulfurous acid: Difference between revisions
ref |
Hairy Dude (talk | contribs) {{block indent}} rather than abusing invalid deflist markup Tags: Mobile edit Mobile web edit Advanced mobile edit |
||
| Line 65: | Line 65: | ||
[[Raman spectroscopy|Raman spectra]] of solutions of [[sulfur dioxide]] in water show only signals due to the {{chem2|SO2}} molecule and the bisulfite ion, {{chem2|HSO3−}}.<ref>{{Jolly2nd}}</ref> The intensities of the signals are consistent with the following [[chemical equilibrium|equilibrium]]: |
[[Raman spectroscopy|Raman spectra]] of solutions of [[sulfur dioxide]] in water show only signals due to the {{chem2|SO2}} molecule and the bisulfite ion, {{chem2|HSO3−}}.<ref>{{Jolly2nd}}</ref> The intensities of the signals are consistent with the following [[chemical equilibrium|equilibrium]]: |
||
{{block indent|1={{chem2|SO2 + H2O ⇌ HSO3− + H+}}{{spaces|10}}''K''<sub>a</sub> = 1.54{{e|−2}}; p''K''<sub>a</sub> = 1.81.}} |
|||
<sup>17</sup>O [[NMR spectroscopy]] provided evidence that solutions of sulfurous acid and protonated sulfites contain a mixture of isomers, which is in equilibrium:<ref name="InorgChem">{{cite book |
<sup>17</sup>O [[NMR spectroscopy]] provided evidence that solutions of sulfurous acid and protonated sulfites contain a mixture of isomers, which is in equilibrium:<ref name="InorgChem">{{cite book |
||
| title = Inorganic Chemistry, 3rd Edition |
| title = Inorganic Chemistry, 3rd Edition |
||
| Line 76: | Line 78: | ||
| page = 520 |
| page = 520 |
||
}}</ref> |
}}</ref> |
||
{{block indent|{{chem2|[H\sOSO2]− ⇌ [H\sSO3]−}}}} |
|||
Attempts to concentrate the solutions of sulfurous acid simply reverses the equilibrium, producing sulfur dioxde and water vapor. A [[clathrate]] with the formul a{{chem2|4SO2*23H2O}} has been crystallised. It decomposes above 7 °C. Anhydrous sulfurous acid {{chem2|H2SO3}} has not been isolated. |
Attempts to concentrate the solutions of sulfurous acid simply reverses the equilibrium, producing sulfur dioxde and water vapor. A [[clathrate]] with the formul a{{chem2|4SO2*23H2O}} has been crystallised. It decomposes above 7 °C. Anhydrous sulfurous acid {{chem2|H2SO3}} has not been isolated. |
||
Revision as of 12:00, 13 November 2022
| |
| |
| Names | |
|---|---|
| IUPAC name
Sulfurous acid
| |
| Other names
Sulfuric(IV) acid
| |
| Identifiers | |
3D model (JSmol)
|
|
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.029.066 |
| EC Number |
|
| 1458 | |
| KEGG | |
PubChem CID
|
|
| UNII | |
CompTox Dashboard (EPA)
|
|
| |
| |
| Properties | |
| H2SO3 | |
| Molar mass | 82.07 g/mol |
| Acidity (pKa) | 1.857, 7.172 |
| Conjugate base | 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
|
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).
| |
Sulfurous acid (also sulfuric(IV) acid, sulphurous acid (UK), sulphuric(IV) acid (UK)) is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution,[1] but the molecule has been detected in the gas phase.[2] 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.[3]
Raman spectra of solutions of sulfur dioxide in water show only signals due to the SO2 molecule and the bisulfite ion, HSO−3.[4] The intensities of the signals are consistent with the following equilibrium:
17O NMR spectroscopy provided evidence that solutions of sulfurous acid and protonated sulfites contain a mixture of isomers, which is in equilibrium:[5]
Attempts to concentrate the solutions of sulfurous acid simply reverses the equilibrium, producing sulfur dioxde and water vapor. A clathrate with the formul a4SO2·23H2O has been crystallised. It decomposes above 7 °C. Anhydrous sulfurous acid H2SO3 has not been isolated.
Uses
Aqueous solutions of sulfur dioxide, which sometimes are referred to as sulfurous acid, are used as reducing agents and as disinfectants, as are solutions of bisulfite and sulfite salts. They are oxidised to sulfuric acid or sulfate by accepting another oxygen atom.[6]
See also
References
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 719. ISBN 978-0-08-037941-8.
- ^ D. Sülzle; M. Verhoeven; J. K. Terlouw; H. Schwarz (1988). "Generation and Characterization of Sulfurous Acid (H2SO3) and of Its Radical Cation as Stable Species in the Gas Phase". Angew. Chem. Int. Ed. Engl. 27 (11): 1533–4. doi:10.1002/anie.198815331.
- ^ McQuarrie; Rock (1987). General Chemistry (2nd ed.). New York: W.H. Freeman and Company. p. 243. ISBN 0-7167-1806-5.
- ^ Jolly, William L. (1991). Modern Inorganic Chemistry (2nd ed.). New York: McGraw-Hill. ISBN 0-07-032768-8.
- ^ Catherine E. Housecroft; Alan G. Sharpe (2008). "Chapter 16: The group 16 elements". Inorganic Chemistry, 3rd Edition. Pearson. p. 520. ISBN 978-0-13-175553-6.
- ^ L. Kolditz, Anorganische Chemie, VEB Deutscher Verlag der Wissenschaften, Berlin 1983, S. 476.