Carbon monoxide
Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest carbon oxide. In coordination complexes, the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry.
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| Names | |||
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| IUPAC name
Carbon monoxide | |||
| Other names
Carbonic oxide gas Carbon protoxide Oxide of carbon Protoxide of carbon Carbonous oxide Carbonous acid gas Carbon(II) oxide Breath of carbon Oxygenated carbon Carbate Carbonyl Water gas Hydrocarbon gas Fuel gas Rauchgas Carbonic inflammable air Heavy inflammable air White damp Fire Damp Powder Gas Illuminating gas Dowson gas Mond gas Power gas Producer gas Blast furnace gas Coal gas Phlogiston Car gas | |||
| Identifiers | |||
3D model (JSmol) |
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| 3587264 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.010.118 | ||
| EC Number |
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| 421 | |||
| KEGG | |||
| MeSH | Carbon+monoxide | ||
PubChem CID |
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| RTECS number |
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| UNII | |||
| UN number | 1016 | ||
CompTox Dashboard (EPA) |
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| Properties | |||
| CO | |||
| Molar mass | 28.010 g·mol−1 | ||
| Appearance | Colorless | ||
| Odor | Odorless | ||
| Density |
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| Melting point | −205.02 °C (−337.04 °F; 68.13 K) | ||
| Boiling point | −191.5 °C (−312.7 °F; 81.6 K) | ||
| 27.6 mg/L (25 °C) | |||
| Solubility | soluble in chloroform, acetic acid, ethyl acetate, ethanol, ammonium hydroxide, benzene | ||
Henry's law constant (kH) |
1.04 atm·m3/mol | ||
| −9.8·10−6 cm3/mol | |||
Refractive index (nD) |
1.0003364 | ||
| 0.122 D | |||
| Thermochemistry | |||
Heat capacity (C) |
29.1 J/(K·mol) | ||
Std molar entropy (S⦵298) |
197.7 J/(K·mol) | ||
Std enthalpy of formation (ΔfH⦵298) |
−110.5 kJ/mol | ||
Std enthalpy of combustion (ΔcH⦵298) |
−283.0 kJ/mol | ||
| Pharmacology | |||
| V04CX08 (WHO) | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards |
Poisonous by inhalation | ||
| GHS labelling: | |||
| Danger | |||
| H220, H331, H360, H372, H420 | |||
| P201, P202, P210, P251, P260, P261, P264, P270, P281, P304+P340, P308+P313, P311, P314, P321, P377, P381, P403, P403+P233, P405, P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | −191 °C (−311.8 °F; 82.1 K) | ||
| 609 °C (1,128 °F; 882 K) | |||
| Explosive limits | 12.5–74.2% | ||
| Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration) |
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LCLo (lowest published) |
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| NIOSH (US health exposure limits): | |||
PEL (Permissible) |
TWA 50 ppm (55 mg/m3) | ||
REL (Recommended) |
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IDLH (Immediate danger) |
1200 ppm | ||
| Safety data sheet (SDS) | ICSC 0023 | ||
| Related compounds | |||
Other anions |
Carbon monosulfide | ||
Other cations |
Silicon monoxide Germanium monoxide Tin(II) oxide Lead(II) oxide | ||
Related carbon oxides |
Carbon dioxide Carbon suboxide Oxocarbons | ||
| Supplementary data page | |||
| Carbon monoxide (data page) | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |||
The most common source of carbon monoxide is the partial combustion of carbon-containing compounds. Numerous environmental and biological sources generate carbon monoxide. In industry, carbon monoxide is important in the production of many compounds, including drugs, fragrances, and fuels. Upon emission into the atmosphere, carbon monoxide affects several processes that contribute to climate change.
Carbon monoxide has important biological roles across phylogenetic kingdoms. It is produced by many organisms, including humans. In mammalian physiology, carbon monoxide is a classical example of hormesis where low concentrations serve as an endogenous neurotransmitter (gasotransmitter) and high concentrations are toxic resulting in carbon monoxide poisoning. It is isoelectronic with cyanide anion CN−.