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| Ozone | |
|---|---|
| 200px | |
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| IUPAC name | Trioxygen |
| Other names | 2λ4-trioxidiene; catena-trioxygen |
| Identifiers | |
| CAS number | |
| PubChem | |
| EC number | 233–069–2 |
| MeSH | |
| ChEBI | CHEBI:25812 |
| RTECS number | RS8225000 |
| SMILES | [O-][O+]=O |
| Gmelin Reference | 1101 |
| Properties | |
| Molecular formula | O3 |
| Molar mass | 47.98 g mol-1 |
| Appearance | Colourless to pale blue gas< |
| Odor | Pungent |
| Density | 2.144 mg cm−3 (at 0 °C) |
| Melting point | -192 °C, 81 K, -314 °F |
| Boiling point | |
| Solubility in water | 1.05 g L−1 (at 0 °C) |
| Solubility in other solvents | Very soluble in CCl4, sulfuric acid |
| Vapor pressure | 55.7 atm (−12.15 °C or 10.13 °F; 261.00 K) |
| +6.7·10−6 cm3/mol | |
| Refractive index (nD) | 1.2226 (liquid), 1.00052 (gas, STP, 546 nm — note high dispersion) |
| Structure | |
| Space group | C2v |
| Coordination geometry | Digonal |
| Molecular shape | Dihedral |
| Hybridisation | sp2 for O1 |
| Dipole moment | 0.53 D |
| Thermochemistry | |
| Std enthalpy of formation ΔfH | 142.67 kJ mol−1 |
| Standard molar entropy S | 238.92 J K−1 mol−1 |
| Hazards | |
| NFPA 704 |
0 4 4 |
| U.S. Permissible exposure limit (PEL) | TWA 0.1 ppm (0.2 mg/m3) |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Ozone, or trioxygen, is a chemical with the symbol O3. This means one molecule of ozone is made of three oxygen atoms. Ozone is rarely called trioxygen, even though this is its IUPAC systematic name. Ozone is formed from oxygen gas (O2) by the action of ultraviolet light and also atmospheric electrical discharges. It is present in low concentrations throughout the Earth's atmosphere. In total, ozone makes up only 0.6 ppm (parts per million) of the atmosphere by volume.
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