Ozone - Simple English Wikipedia, the free encyclopedia

Ozone

Names
IUPAC name Trioxygen
Other names 2λ4-trioxidiene; catena-trioxygen
Identifiers
CAS Number	10028-15-6 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:25812 Y
ChemSpider	23208 Y
ECHA InfoCard	100.030.051
EC Number	233–069–2
Gmelin Reference	1101
IUPHAR/BPS	6297
MeSH	Ozone
PubChem CID	24823
RTECS number	RS8225000
UNII	66H7ZZK23N Y
CompTox Dashboard (EPA)	DTXSID0021098
SMILES [O-][O+]=O
Properties
Chemical formula	O3
Molar mass	48.00 g·mol−1
Appearance	Colourless 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
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[1] (−12.15 °C or 10.13 °F or 261.00 K)[a]
Magnetic susceptibility (χ)	+6.7·10−6 cm3/mol
Refractive index (nD)	1.2226 (liquid), 1.00052 (gas, STP, 546 nm — note high dispersion)[2]
Structure
Space group	C2v
Coordination geometry	Digonal
Molecular shape	Dihedral
Hybridisation	sp2 for O1
Dipole moment	0.53 D
Thermochemistry
Std enthalpy of formation ΔfHo298	142.67 kJ mol−1
Standard molar entropy So298	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)
Related compounds
Related compounds	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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.^[3] 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.

Ozone is important to life on planet Earth. There is a portion of the stratosphere with a high concentration of ozone, called the ozone layer. The ozone layer is 10 to 50 kilometers above the ground. It filters out damaging ultraviolet radiation from the Sun,^[4] like a kind of sun screen. Without this ozone layer things would not have been able to live on the surface of our planet. The ozone layer also absorbs a lot of heat from the sun's rays.

However, ozone is toxic to animals and plants above concentrations of about 0.1 ppm. In humans, it can cause nasal and throat irritation, and nausea.^[5] Extended exposure can cause lung oedema.^[5] 0.100 ppm is the maximum allowable limit for industrial, public, or occupied spaces in England, Japan, France, the Netherlands and Germany.^[5]

The ozone near the ground forms because of pollution. It is formed by a chemical reaction between volatile organic compounds and nitrogen oxides. These molecules are common pollutants in cities. Ozone at ground level creates smog.^[6]

Notes

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