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Names | |||
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IUPAC name
Trioxygen
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Identifiers | |||
3D model (JSmol)
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ChEBI | |||
ChemSpider | |||
ECHA InfoCard | 100.030.051 | ||
EC Number | 233–069–2 | ||
1101 | |||
MeSH | Ozone | ||
PubChem CID
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RTECS number | RS8225000 | ||
UNII | |||
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Properties | |||
O3 | |||
Molar mass | 48.00 g·mol−1 | ||
Appearance | colorless to pale blue gas | ||
Odor | pungent | ||
Density | 2.144 mg cm−3 (at 0 °C) | ||
Melting point | −192.2 °C; −313.9 °F; 81.0 K | ||
Boiling point | −112 °C; −170 °F; 161 K | ||
1.05 g L−1 (at 0 °C) | |||
Solubility | very soluble in CCl4, sulfuric acid | ||
Vapor pressure | >1 atm (20 °C) | ||
+6.7·10−6 cm3/mol | |||
Refractive index (nD)
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1.2226 (liquid), 1.00052 (gas, STP, 546 nm — note high dispersion) | ||
Structure | |||
C2v | |||
Digonal | |||
Dihedral | |||
Hybridisation | sp2 for O1 | ||
0.53 D | |||
Thermochemistry | |||
Std molar
entropy (S |
238.92 J K−1 mol−1 | ||
Std enthalpy of
formation (ΔfH |
142.67 kJ mol−1 | ||
Hazards | |||
EU classification (DSD) (outdated)
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O T+ C Xi | ||
NFPA 704 | |||
Lethal dose or concentration (LD, LC): | |||
LCLo (lowest published)
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12.6 ppm (mouse, 3 hr) 50 ppm (human, 30 min) 36 ppm (rabbit, 3 hr) 21 ppm (mouse, 3 hr) 21.8 ppm (rat, 3 hr) 24.8 ppm (guinea pig, 3 hr) 4.8 ppm (rat, 4 hr) |
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US health exposure limits (NIOSH): | |||
PEL (Permissible)
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TWA 0.1 ppm (0.2 mg/m3) | ||
REL (Recommended)
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C 0.1 ppm (0.2 mg/m3) | ||
IDLH (Immediate danger)
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5 ppm | ||
Related compounds | |||
Related compounds
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Sulfur dioxide Trisulfur Disulfur monoxide Cyclic ozone |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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what is ?) | (|||
Infobox references | |||
Ozone /ˈoʊzoʊn/ (systematically named 1λ1,3λ1-trioxidane and catena-trioxygen), or trioxygen, is an inorganic molecule with the chemical formula O
3. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope O
2, breaking down in the lower atmosphere to O
2 or dioxygen. Ozone is formed from dioxygen by the action of ultraviolet light and also atmospheric electrical discharges, and is present in low concentrations throughout the Earth's atmosphere (stratosphere). In total, ozone makes up only ppm of the atmosphere. 0.6
Ozone's odour is sharp, reminiscent of chlorine, and detectable by many people at concentrations of as little as ppb in air. Ozone's O3 structure was determined in 1865. The molecule was later proven to have a bent structure and to be 100 diamagnetic. In standard conditions, ozone is a pale blue gas that condenses at progressively cryogenic temperatures to a dark blue liquid and finally a violet-black solid. Ozone's instability with regard to more common dioxygen is such that both concentrated gas and liquid ozone may decompose explosively at elevated temperatures or fast warming to the boiling point. It is therefore used commercially only in low concentrations.