Sulfur dioxide
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General |
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| Name | Sulfur dioxide |
| Chemical formula | SO2 |
| Appearance | Colourless gas |
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Physical |
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| Formula weight | 64.1 g/mol |
| Melting point | 198 K (-75 °C) |
| Boiling point | 263 K (-10 °C) |
| Density | 1400 kg/m3 (liquid) |
| Solubility | 9.4 g in 100 g water |
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Thermochemistry |
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| ΔfH |
-296.84 kJ/mol |
| ΔfH |
? kJ/mol |
| ΔfH |
? kJ/mol |
| S |
248.21 J/(mol·K) |
| S |
? J/(mol·K) |
| S |
? J/(mol·K) |
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Safety | |
| Ingestion | Relatively low toxicity, may cause nausea and vomiting. Long term hazards known. |
| Inhalation | Extreme irritation. |
| Skin | Hazardous when cryogenic or compressed. |
| Eyes | Hazardous when cryogenic or compressed. |
| More info | Hazardous Chemical Database (http://ull.chemistry.uakron.edu/erd/chemicals1/8/7104.html) |
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SI units were used where possible. Unless otherwise stated, standard conditions were used. | |
Sulfur dioxide (or sulphur dioxide) has the chemical formula SO2. The gas is irritating to the lungs and is frequently described as smelling of burning sulfur.
It is produced by volcanoes and in various industrial processes. In particular, poor-quality coal and petroleum contain sulfur compounds, and generate sulfur dioxide when burned: the gas reacts with water and atmospheric oxygen to form sulfurous acid (H2SO3) and thus acid rain.
| Contents |
Preparation of sulfur dioxide for chemical production
Sulfur dioxide is often prepared by burning sulfur in air:
S(s) + O2 (g) → SO2 (g)
Hydrogen sulfide from crude oil may also be burned.
H2S (g) + O2 (g) → H2 (g) + SO2 (g)
Sulfide ores such as iron pyrites and sphalerite (zinc blende) may also be used:
4 FeS2 (s) + 11 O2 (g) → 2 Fe2O3 (s) + 8 SO2 (g)
2 ZnS (s) + 3 O2 (g) → 2 ZnO (s) + 2 SO2 (g)
When anhydrous CaSO4, is heated with coke and sand in the manufacture of cement, CaSiO3, sulfur dioxide is a by-product.
2 CaSO4 (s) + 2 SiO2 (s) + C (s) → 2 CaSiO3 + 2 SO2 (g) + CO2
Flue gas desulfurisation in power stations releases SO2 for the process.
Uses
Sulfur dioxide is sometimes used as a preservative in alcoholic drinks, or dried apricots and other fruits. The preservative is used to maintain the apperance of the fruit rather than prevent rotting. This can give fruit a distinctive chemical taste. H2SO3 is also called "hydrogen sulfite" or sulfurous acid.
See also:
External links
- Food Intolerance Network (http://www.fedupwithfoodadditives.info/factsheets/Factsulphites.htm) - Sulphite factsheet
- Sulphur Dioxide, Molecule of the Month (http://www.chm.bris.ac.uk/motm/so2/so2h.htm)de:Schwefeldioxid
es:Dióxido_de_azufre fr:Dioxyde de soufre it:Diossido di zolfo nl:Zwaveldioxide ja:二酸化硫黄 pl:Dwutlenek siarki ru:Диоксид серы sv:Svaveldioxid zh:二氧化硫