Carbon monoxide

Carbon monoxide
Ball-and-stick model of carbon monoxide
Ball-and-stick model of carbon monoxide
Spamodel of carbon monoxide
Spamodel of carbon monoxide
model of carbon monoxide
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
Water gas
Hydrocarbon gas
Fuel gas
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
Car gas
3D model (JSmol)
ECHA InfoCard 100.010.118 Edit this at Wikidata
EC Number
  • 211-128-3
MeSH Carbon+monoxide
RTECS number
  • FG3500000
UN number 1016
  • InChI=1S/CO/c1-2 checkY
  • InChI=1/CO/c1-2
  • [C-]#[O+]
Molar mass 28.010 g·mol−1
Appearance Colorless
Odor Odorless
  • 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)
27.6 mg/L (25 °C)
Solubility soluble in chloroform, acetic acid, ethyl acetate, ethanol, ammonium hydroxide, benzene
1.04 atm·m3/mol
−9.8·10−6 cm3/mol
0.122 D
29.1 J/(K·mol)
197.7 J/(K·mol)
−110.5 kJ/mol
−283.0 kJ/mol
V04CX08 (WHO)
Occupational safety and health (OHS/OSH):
Main hazards
Poisonous by inhalation[1]
GHS labelling:
GHS02: FlammableGHS06: ToxicGHS08: Health hazard
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):
  • 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)[2]
  • 4000 ppm (human, 30 min)
  • 5000 ppm (human, 5 min)[2]
NIOSH (US health exposure limits):[1]
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
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).
checkY verify (what is checkY☒N ?)

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] Upon emission into the atmosphere, carbon monoxide affects several processes that contribute to climate change.[7]

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.

  1. ^ a b NIOSH Pocket Guide to Chemical Hazards. "#0105". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b "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". US NOAA Office of Response and Restoration.
  5. ^ Cite error: The named reference Ull was invoked but never defined (see the help page).
  6. ^ Bierhals, Jürgen (2001). "Carbon Monoxide". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a05_203. ISBN 3527306730.
  7. ^ Voiland, Adam. "Fourteen years of carbon monoxide from MOPITT". Climate Change: Vital Signs of the Planet. Retrieved 2022-03-04.