Carbon monoxide

Carbon monoxide
Names
	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
CAS Number	630-08-0 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	3587264
ChEBI	CHEBI:17245 ;
ChEMBL	ChEMBL1231840;
ChemSpider	275 ;
ECHA InfoCard	100.010.118
EC Number	211-128-3;
Gmelin Reference	421
KEGG	D09706 ;
MeSH	Carbon+monoxide
PubChem CID	281;
RTECS number	FG3500000;
UNII	7U1EE4V452 ;
UN number	1016
CompTox Dashboard (EPA)	DTXSID5027273 ;
	InChI InChI=1S/CO/c1-2 Key: UGFAIRIUMAVXCW-UHFFFAOYSA-N ; InChI=1/CO/c1-2 Key: UGFAIRIUMAVXCW-UHFFFAOYAT;
	SMILES [C-]#[O+];
Properties
Chemical formula	CO
Molar mass	28.010 g·mol−1
Appearance	Colorless
Odor	Odorless
Density	789 kg/m3, liquid; 1.250 kg/m3 at 0 °C, 1 atm; 1.145 kg/m3 at 25 °C, 1 atm;
Melting point	−205.02 °C (−337.04 °F; 68.13 K)
Boiling point	−191.5 °C (−312.7 °F; 81.6 K)
Solubility in water	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
Magnetic susceptibility (χ)	−9.8·10−6 cm3/mol
Refractive index (nD)	1.0003364
Dipole moment	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
ATC code	V04CX08 (WHO)
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Poisonous by inhalation
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H220, H331, H360, H372, H420
Precautionary statements	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)	3 4 0
Flash point	−191 °C (−311.8 °F; 82.1 K)
Autoignition; temperature	609 °C (1,128 °F; 882 K)
Explosive limits	12.5–74.2%
	Lethal dose or concentration (LD, LC):
LC50 (median concentration)	8636 ppm (rat, 15 min); 5207 ppm (rat, 30 min); 1784 ppm (rat, 4 h); 2414 ppm (mouse, 4 h); 5647 ppm (guinea pig, 4 h);
LCLo (lowest published)	4000 ppm (human, 30 min); 5000 ppm (human, 5 min);
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 50 ppm (55 mg/m3)
REL (Recommended)	TWA 35 ppm (40 mg/m3); C 200 ppm (229 mg/m3);
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). verify (what is ?) Infobox references

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.^[5]

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.^[6]

Indoors CO is one of the most acutely toxic contaminants affecting indoor air quality. CO may be emitted from tobacco smoke and generated from malfunctioning fuel-burning stoves (wood, kerosene, natural gas, propane) and fuel-burning heating systems (wood, oil, natural gas) and from blocked flues connected to these appliances.^[7] Carbon monoxide poisoning is the most common type of fatal air poisoning in many countries.^[8]^[7]^[9]

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 both cyanide anion CN⁻ and molecular nitrogen N₂.

^ ^a ^b NIOSH Pocket Guide to Chemical Hazards. "#0105". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b "Carbon monoxide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ Richard, Pohanish (2012). Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens (2 ed.). Elsevier. p. 572. ISBN 978-1-4377-7869-4. Retrieved 5 September 2015.
^ "Carbon Monoxide - CAMEO Chemicals". cameochemicals.noaa.gov. US NOAA Office of Response and Restoration.
^ Bierhals, Jürgen (2001). "Carbon Monoxide". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_203. ISBN 3527306730.
^ Bierhals, Jürgen (2001). "Carbon Monoxide". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a05_203. ISBN 3527306730.
^ ^a ^b Myers, Isabella (February 2022). The efficient operation of regulation and legislation: An holistic approach to understanding the effect of Carbon Monoxide on mortality (PDF). CO Research Trust.
^ Cite error: The named reference UK Health Security Agency was invoked but never defined (see the help page).
^ Cite error: The named reference Dent-2024 was invoked but never defined (see the help page).

[PGCH-1] NIOSH Pocket Guide to Chemical Hazards. "#0105". National Institute for Occupational Safety and Health (NIOSH).

[IDLH-2] "Carbon monoxide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).

[3] Richard, Pohanish (2012). Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens (2 ed.). Elsevier. p. 572. ISBN 978-1-4377-7869-4. Retrieved 5 September 2015.

[4] "Carbon Monoxide - CAMEO Chemicals". cameochemicals.noaa.gov. US NOAA Office of Response and Restoration.

[Ull-5] Bierhals, Jürgen (2001). "Carbon Monoxide". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_203. ISBN 3527306730.

[6] Bierhals, Jürgen (2001). "Carbon Monoxide". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a05_203. ISBN 3527306730.

[Myers-2022-7] Myers, Isabella (February 2022). The efficient operation of regulation and legislation: An holistic approach to understanding the effect of Carbon Monoxide on mortality (PDF). CO Research Trust.

[UK_Health_Security_Agency-8] Cite error: The named reference UK Health Security Agency was invoked but never defined (see the help page).

[Dent-2024-9] Cite error: The named reference Dent-2024 was invoked but never defined (see the help page).

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