The Nitrous oxide reference article from the English Wikipedia on 24-Jul-2004
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Nitrous oxide

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Structure of Nitrous oxide


Name Dinitrogen oxide
Chemical formula N2O
Appearance Colourless gas


Formula weight 44.0 amu
Melting point 182 K (-91 °C)
Boiling point 185 K (-88 °C)
Density 1.2 ×103 kg/m3 (liquid)
Solubility 0.112 g in 100g water


ΔfH0gas 82.05 kJ/mol
ΔfH0liquid ? kJ/mol
ΔfH0solid ? kJ/mol
S0gas, 1 bar 219.96 J/mol·K
S0liquid, 1 bar ? J/mol·K
S0solid ? J/mol·K


Inhalation See main text. May cause asphyxiation without warning.
Skin Hazardous when cryogenic or compressed.
Eyes Hazardous when cryogenic or compressed.
More info Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used.

Disclaimer and references

Nitrous oxide, also known as dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O. Under room conditions it is a colourless non-flammable gas, with a pleasant slightly sweet odor. It is commonly known as laughing gas for the exhilarating effects of inhaling it. It is used in surgery and dentistry for its anaesthetic and analgesic effects.

Table of contents
1 Chemistry
2 History
3 Uses
4 Nitrous oxide pollution


The structure of the nitrous oxide molecule is a linear chain of a nitrogen atom bound to a second nitrogen, which in turn is bound to an oxygen atom. It is a resonance structure of

Nitrous oxide N2O should not be confused with nitric oxide NO and nitrogen dioxide NO2, both of which are extremely corrosive toxins; nitrogen dioxide, produced by the combination of nitric oxide with oxygen, reacts with water to form nitric acid.

Nitrous oxide can also be used to produce nitrites by mixing it with boiling alkali metals and to oxidize organic compounds at high temperatures.


The gas was discovered by Joseph Priestleyin 1772; Humphry Davy in the 1790s tested the gas on himself and some of his friends (including the poets Samuel Taylor Coleridge and Robert Southey). They soon realised that nitrous oxide considerably dulled the sensation of pain, even if the inhaler were still semi-conscious, and so it came into use as an anaesthetic, particularly by dentists.


Inhalant effects — laughing Gas

There have been examples of abuse of nitrous oxide for its inhalant effects. The fear of staff abusing the gas is the main reason that it is rarely used today. While the gas itself is not toxic, death can result if it is inhaled in such a way that not enough oxygen is breathed in, especially if the user becomes unconscious. Long-term use in large quantities has been associated with symptoms similar to vitamin B12 deficiency: anemia and neuropathy.

Nitrous Oxide is a dissociative which causes euphoria, dizziness, and, in some cases, a mild aphrodesiac effect. It can also result in mild nausea or lingering dizziness if to much is inhaled in to short a time. Mainly because of its short-lived effect and ease of access it can occasionally be habit-forming.

In California, and roughly 30 other states, inhalation of nitrous oxide "for the purpose of causing euphoria, or for the purpose of changing in any manner, one’s mental processes," is a criminal offense. (See, Cal. Pen. Code, Sec. 381b.) The Center for Cognitive Liberty & Ethics, a nonprofit law and policy center in the United States, contends that such laws are unconstitional "prior restraints on speech" and constitute "cognitive censorhip."

Aerosol propellant

The gas is licensed for use as a food additive, specifically as an aerosol propellant. Its most common uses in this context are in aerosol whipped cream canisters and as an inert gas used to displace staleness-inducing oxygen when filling packages of potato chips and other similar snack foods.

The gas is excellently soluble in fatty compounds. In aerosol whipped cream, it is dissolved in the fatty cream until it leaves the can, when it becomes gaseous and thus creates foam. The anaesthetic function of nitrous oxide is not completely understood, but it is thought that the gas interacts with the plasma membranes of nerve cells in the brain and thus affects the communication among such cells at their synapses.

Car racing

In car racing, nitrous oxide is sometimes injected into the intake manifold (or just prior to the intake manifold) to increase power: even though the gas itself is not flammable, it delivers more oxygen than atmospheric air by breaking down at elevated temperatures, thus allowing the engine to burn more fuel and air. Additionally, since nitrous oxide is stored as a liquid, the evaporation of liquid nitrous oxide in the intake manifold causes a large drop in intake charge temperature. This results in a smaller, denser charge, and can reduce detonation, as well as increase power available to the engine.

In this context, nitrous oxide is sometimes called Nitrous.

This technique was used in World War II to boost the power of aircraft engines, particularly by the Luftwaffe which had less access to fuel with high octane ratings than did the Royal Air Force and United States Air Force.

It is very important with nitrous oxide augmentation of internal combustion engines to maintain temperatures and fuel levels so as to prevent preignition, or detonation (sometimes referred to as knocking).

Nitrous oxide pollution

Oxides of Nitrogen, Nitrous Oxide included, are greenhouse gas 270 times more potent than Carbon dioxide.

Additionally, when oxides of nitrogen are combined with hydrocarbons and sunlight they produce what is called photochemical smog. This is the brown stuff you see hovering over cities such as Los Angeles and Stockton in California.

The CAS number of nitrous oxide is 10024-97-2 and its UN number is 1070.