Nitrous oxide

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Nitrous oxide
Melting nitrous oxide by ChemicalForce.jpg
Frozen nitrous oxide melting in a vial
IUPAC name
Dinitrogen monoxide
Other names
Dinitrogen monoxide
Dinitrogen oxide
Hyponitrous oxide
Laughing gas
Protoxide of nitrogen
Sweet air
Molar mass 44.013 g/mol
Appearance Colorless gas
Odor Slightly sweetish
Density 1.266 g/L (-88.9 °C)
1.977 g/L (STP)
Melting point −90.86 °C (−131.55 °F; 182.29 K)
Boiling point −88.48 °C (−127.26 °F; 184.67 K)
1.5 g/L (15 °C)
Solubility Soluble in alcohols, ethers, sulfuric acid
Vapor pressure 4.29·104 mmHg at 25 °C
219.96 J·K−1·mol−1
82.05 kJ/mol
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Related compounds
Related compounds
Nitric oxide
Nitrogen dioxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Nitrous oxide, also known as dinitrogen monoxide, nitrogen protoxide, nitrous, nitro, NOS or more popular laughing gas is a chemical compound with the formula N2O.



Nitrous oxide is an oxidizer. Unlike other nitrogen oxides, nitrous oxide does not react with water to form nitric acids.


Nitrous oxide is a colorless, non-flammable gas, with a slightly sweet odor and taste. It is poorly soluble in water, but more soluble in several organic solvents such as ethanol, diethyl ether, as well as sulfuric acid. It is known as "laughing gas" due to the euphoric effects of inhaling it, a property that has led to its recreational use as a dissociative anaesthetic.


Nitrous oxide is available as whippets. Medical grade nitrous oxide tanks are available in dentistry, though they are not easy to acquire by the average person.


Nitrous oxide is prepared by the careful decomposition of ammonium nitrate, which results in nitrous oxide and water vapor.

NH4NO3 → N2O + 2 H2O

Due to the very low amount of secondary products, this reaction is preferred by many chemists, albeit molten ammonium nitrate can explode very easily, making this route dangerous.

A less dangerous route involves heating hydroxylammonium chloride with sodium nitrite yields nitrous oxide.[1]

NH2OH·HCl + NaNO2 → N2O + NaCl + 2 H2O

Another way of preparing nitrous oxide involves heating a mixture of ammonium sulfate and sodium nitrate.

2 NaNO3 + (NH4)2SO4 → Na2SO4 + 2 N2O+ 4 H2O.

Another route involves heating a mixture of urea, nitric acid and sulfuric acid between 40-100°C and purifying N2O from resulting gaseous products:

2 (NH2)2CO + 2 HNO3 + H2SO4 → 2 N2O + 2 CO2 + (NH4)2SO4 + 2 H2O[2]


  • Rockets
  • Sodium azide synthesis
  • Laughing gas (medical grade only!)



Nitrous oxide has low toxicity and posses analgesic properties. It can be very addictive and its misuse can have a moderate to serious psychological and nervous impact. Nitrogen protoxide is a strong oxidizer and should be kept away from any combustible materials.

When obtaining it from ammonium nitrate, it's imperative to prevent the temperature from rising too high, as it may cause an explosion if large quantities are used. This isn't an issue with commercial AN, as it contains gypsum which acts as a stabilizer and reduces the risk of explosion.


Nitrous oxide cylinders should be stored in cold places, away from any organic materials, as it is a strong oxidizer and a fire hazard.


Nitrous oxide will eventually break down in air into nitrogen and oxygen, and does not generate any toxic byproducts. This reaction is sped up by reducing agents.



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