Carbon monoxide

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Carbon monoxide
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Beilstein Reference 3587264
Gmelin Reference 421
MeSH {{{value}}}
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RTECS number FG3500000
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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 Template:Chembox CalcTemperatures
Boiling point Template:Chembox CalcTemperatures
Solubility soluble in chloroform, acetic acid, ethyl acetate, ethanol, ammonium hydroxide, benzene
kH 1.04 atm·m3/mol
0.122 D
Std enthalpy of
−110.5 kJ/mol
Std enthalpy of
−283.4 kJ/mol
Standard molar
197.7 J/(mol·K)
Specific heat capacity, C 29.1 J/(K·mol)
EU classification Flammable F+ Very Toxic T+
NFPA 704
R-phrases Template:R61 Template:R12 Template:R26 R48/23
S-phrases S53 S45
Explosive limits 12.5–74.2%
U.S. Permissible
exposure limit (PEL)
TWA 50 ppm (55 mg/m3)
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Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. It consists of one carbon atom covalently bonded to one oxygen atom. It is made when carbon compounds burn and there is not enough oxygen. It is a good fuel and burns in air with a blue flame, making carbon dioxide. It is very toxic, but it is useful for modern technology as well.

The most important use for carbon monoxide in industry is making iron from iron ore. The carbon monoxide takes the oxygen from the iron ore when heated in a large oven called a blast furnace. Liquid metal iron is left behind. The carbon monoxide turns into carbon dioxide.

Carbon monoxide can accidentally form when there is too little air to burn all the fuel into carbon dioxide. Such a situation may happen if the oven shutters are closed too early or if a mobile cooker is used in a small tent with no ventilation (Ventilation is fresh air coming in and smoke going out). Many people have died from carbon monoxide poisoning. Carbon monoxide poisoning can cause feelings of paranoia and hallucinations, and has been determined to be a major cause of "haunted" houses. Small amounts of it are found in coal gas, a fuel produced by heating coal without any air.


Despite that it is a poison, carbon monoxide is very useful in chemical industry so lots of ways of making it have been discovered.[2] Normally we burn coke at high temperature with not enough oxygen. Blast furnaces work this way. The chemical equation for this is:

2C + O2 → 2CO

It can be also made by blowing hot steam through red-hot crushed coke

C + H2O → CO + H2

Carbon monoxide can be used as heating fuel because it burns easily into carbon dioxide. It can also be used as so-called "synthesis gas" for making man-made gasoline in the Fischer-Tropsch process.

During the World War II when petrol was rare and reserved for the military, many cars were converted to use wood gas. It is carbon monoxide made by burning wood chips in insufficient amount of air. The wood gas was made in a special oven called generator, which was carried on the car. The resulting carbon monoxide was then used as fuel for the car itself. Even today there are cars which use wood gas as fuel.


  1. GOV, NOAA Office of Response and Restoration, US. "CARBON MONOXIDE - CAMEO Chemicals - NOAA".
  2. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. Template:Catalog lookup linkScript error: No such module "check isxn"..

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