Carbon monoxide

Carbon monoxide

Names
Preferred IUPAC name Carbon monoxide
Other names Carbon monooxide Carbonous oxide Carbon(II) oxide Carbonyl Flue gas Monoxide
Identifiers
CAS Number	630-08-0 Y
3D model (Jmol)	Interactive image
Beilstein Reference	3587264
ChEBI	CHEBI:17245 Y
ChemSpider	275 Y
ECHA InfoCard	100.010.118
EC Number	211-128-3
Gmelin Reference	421
KEGG	D09706 Y
MeSH	Carbon+monoxide
PubChem	281
RTECS number	FG3500000
UNII	7U1EE4V452 Y
UN number	1016
InChI InChI=1S/CO/c1-2 Y Key: UGFAIRIUMAVXCW-UHFFFAOYSA-N Y InChI=1/CO/c1-2 Key: UGFAIRIUMAVXCW-UHFFFAOYAT
SMILES [C-]#[O+]
Properties
Chemical formula	CO
Molar mass	28.010 g/mol
Appearance	colorless gas
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
Specific heat capacity (C)	29.1 J/K mol
Std molar entropy (So298)	197.7 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−110.5 kJ·mol−1
Std enthalpy of combustion (ΔcHo298)	−283.4 kJ/mol
Hazards
Safety data sheet	See: data page ICSC 0023
EU classification (DSD)	F T+
R-phrases	R61 R12 R26 R48/23
S-phrases	S53 S45
NFPA 704	4 3 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 hr) 2414 ppm (mouse, 4 hr) 5647 ppm (guinea pig, 4 hr)
LCLo (lowest published)	4000 ppm (human, 30 min) 5000 ppm (human, 5 min)
US health exposure limits (NIOSH):
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
Related compounds
Related carbon oxides	Carbon dioxide Carbon suboxide Oxocarbons
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is slightly less dense than air. It is toxic to hemoglobic animals (both invertebrate and vertebrate, including humans) when encountered in concentrations above about 35 ppm, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere, it is spatially variable and short lived, having a role in the formation of ground-level ozone.

Carbon monoxide consists of one carbon atom and one oxygen atom, connected by a triple bond that consists of two covalent bonds as well as one dative covalent bond. It is the simplest oxocarbon and is isoelectronic with the cyanide anion, the nitrosonium cation and molecular nitrogen. In coordination complexes the carbon monoxide ligand is called carbonyl.

Aristotle (384–322 BC) first recorded that burning coals produced toxic fumes. An ancient method of execution was to shut the criminal in a bathing room with smoldering coals. What was not known was the mechanism of death. Greek physician Galen (129–199 AD) speculated that there was a change in the composition of the air that caused harm when inhaled. In 1776, the French chemist de Lassone produced CO by heating zinc oxide with coke, but mistakenly concluded that the gaseous product was hydrogen, as it burned with a blue flame. The gas was identified as a compound containing carbon and oxygen by the Scottish chemist William Cumberland Cruikshank in 1800. Its toxic properties on dogs were thoroughly investigated by Claude Bernard around 1846.