Difference between revisions of "Carbon monoxide"

Revision as of 16:38, 7 August 2015

Structure of carbon monoxide, showing the triple bond between carbon and oxygen atoms.

Carbon monoxide is the inorganic chemical compound with the chemical formula CO, a colorless, odorless gas that is highly toxic to nearly all higher life-forms. Despite its inherent danger, it is a very useful and interesting reagent.

Properties

Chemical

Carbon monoxide burns if ignited in the presence of oxygen, forming carbon dioxide. At high temperatures and pressures it is reactive towards metals, forming metal carbonyls. In organic synthesis, carbon monoxide is a common method for carbonylating a variety of compounds in the presence of a metallic catalyst. It can be reacted with alkenes to form carboxylic acids, its hydrogenation produces methanol. Like carbon, at high temperatures it can reduce metal oxides to their elemental form.

Physical

Carbon monoxide is an acutely toxic, colorless, odorless gas at room temperature. It is very difficult to detect without special equipment.

Availability

Carbon monoxide is a common industrial chemical, but it is unlikely that it can be easily obtained by private citizens given its toxicity. It typically must be prepared in the lab. It can also form (extremely undesirably and dangerously for human life) when one stokes a wood or coal stove improperly, or keeps a working automobile in a closed garage.

Preparation

Carbon monoxide is most often produced by the incomplete combustion of organic materials that occurs without sufficient oxygen. However, it is most often produced for lab use by the dehydration of formic acid or oxalic acid using concentrated sulfuric acid. It can also be prepared in impure form by passing air or oxygen through burning coke or charcoal, and then once more through hot but non-burning charcoal, including volatile compounds and carbon dioxide as impurities. Passing water vapor through red hot coals, or the addition of water to them will give off a flammable mixture of carbon monoxide and hydrogen gas known as "water gas", a type of syngas.

H₂O + C → H₂ + CO (ΔH = +131 kJ/mol)

Projects

• Acetic anhydride synthesis
• Metal carbonyl synthesis
• Make sodium formate
• Make sodium oxalate
• Methanol synthesis

Handling

Safety

Carbon monoxide is very toxic and can easily knock a person unconscious due to oxygen starvation. If someone incapacitated this way is not quickly moved from the environment containing carbon monoxide, death is a near certainty. The symptoms of carbon monoxide poisoning are very easy to dismiss. One must be very careful using or attempting to store carbon monoxide; it is definitely recommended to use it only outside (a fume hood may not be sufficient, but if it must be used then a carbon monoxide detector is a a good idea). Acting irresponsibly with this chemical poses not only a threat to yourself, but to anyone else in the vicinity, so think twice before using it.

Storage

Storing carbon monoxide, both as compressed gas and as carbonyl compounds is dangerous, as in case of a leak, CO will rise and disperse well in the air (because its molar mass is similar to that of nitrogen. A carbon monoxide detector should be used in the immediate area of any potential release of any size.

Disposal

Carbon monoxide should only be released in air if there is no risk of build-up.

References

Relevant Sciencemadness threads