Sulfur dioxide
Sulfur dioxide (also sulphur dioxide) is the chemical compound with the formula SO2. It is a gas. It smells like burnt matches or rotten eggs. It can also cause suffocation. Sulfur dioxide is produced by volcanoes and in various industrial processes. It is also used to protect wine from oxygen and bacteria. It can be produced by burning sulfur. It dissolves in water to produce sulfurous acid. It can be oxidized to trioxide, which is dissolved in sulfuric acid to make more sulfuric acid. It is used to make sulfites.
| Sulfur dioxide | |
|---|---|
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| 160px | |
| IUPAC name | Sulfur dioxide |
| Other names | Sulfurous anhydride Sulfur(IV) oxide |
| Identifiers | |
| CAS number | |
| PubChem | |
| EC number | 231-195-2 |
| KEGG | D05961 |
| MeSH | |
| ChEBI | CHEBI:18422 |
| RTECS number | WS4550000 |
| SMILES | O=S=O |
| Beilstein Reference | 3535237 |
| Gmelin Reference | 1443 |
| Properties | |
| Molecular formula | SO2 |
| Molar mass | 64.066 g mol−1 |
| Appearance | Colorless gas |
| Odor | Pungent; similar to a just-struck match[1] |
| Density | 2.6288 kg m−3 |
| Melting point |
-72 °C, 201 K, -98 °F |
| Boiling point | |
| Solubility in water | 94 g/L[2] forms sulfurous acid |
| Vapor pressure | 237.2 kPa |
| Acidity (pKa) | 1.81 |
| Basicity (pKb) | 12.19 |
| −18.2·10−6 cm3/mol | |
| Viscosity | 0.403 cP (at 0 °C) |
| Structure | |
| C2v | |
| Coordination geometry |
Digonal |
| Molecular shape | Dihedral |
| Dipole moment | 1.62 D |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−296.81 kJ mol−1 |
| Standard molar entropy S |
248.223 J K−1 mol−1 |
| Hazards | |
| NFPA 704 |
0
3
0
|
| U.S. Permissible exposure limit (PEL) |
TWA 5 ppm (13 mg/m3) |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Sulfur Dioxide Media
Two resonance structures of sulfur dioxide
The blue auroral glows of Io's upper atmosphere are caused by volcanic sulfur dioxide.
An experiment showing burning of sulfur in oxygen. A flow-chamber joined to a gas washing bottle (filled with a solution of methyl orange) is being used. The product is sulfur dioxide (SO2) with some traces of sulfur trioxide (SO3). The "smoke" that exits the gas washing bottle is, in fact, a sulfuric acid fog generated in the reaction.
Cheletropic reaction of butadiene with SO2
- Preparationofmtrifluoromethylbenzenesulfonylchloride
US Geological Survey volunteer tests for sulfur dioxide after the 2018 lower Puna eruption.
Schematic of volcano injection of aerosols and gases.
Acid rain-damaged forest in Europe's Black Triangle.
Early 2010s estimates of past and future anthropogenic global sulfur dioxide emissions, including the Representative Concentration Pathways. While no climate change scenario may reach Maximum Feasible Reductions (MFRs), all assume steep declines from today's levels. By 2019, sulfate emission reductions were confirmed to proceed at a very fast rate.
This figure shows the level of agreement between a climate model driven by five factors and the historical temperature record. The negative component identified as "sulfate" is associated with the aerosol emissions blamed for global dimming.
Sources
- ↑ Sulfur dioxide Archived 2019-12-30 at the Wayback Machine, U.S. National Library of Medicine
- ↑ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.
