Dinitrogen tetroxide

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Dinitrogen tetroxide
Dinitrogen tetroxide.svg
Nitrogen dioxide at different temperatures.jpg
IUPAC name Dinitrogen tetraoxide
Other names Dinitrogen(II) oxide(-I)
CAS number 10544-72-6
PubChem 25352
EC number 234-126-4
RTECS number QW9800000
SMILES [O-] [N+](=O)[N+]([O-])=O
Molecular formula N2O4
Molar mass 92.011 g/mol
Appearance colourless liquid / orange gas
Density 1.44246 g/cm3 (liquid, 21 °C)
Melting point

−11.2 °C, 262 K, 12 °F

Boiling point

21.69 °C, 295 K, 71 °F

Solubility in water reacts
Vapor pressure 96 kPa (20 °C)[1]
Refractive index (nD) 1.00112
Molecular shape planar, D2h
Dipole moment zero
Std enthalpy of
+9.16 kJ/mol[2]
Standard molar
304.29 J K−1 mol−1[2]
MSDS External MSDS
EU classification Very toxic (T+)
Corrosive (C)
EU Index 007-002-00-0
NFPA 704

NFPA 704.svg

R-phrases R26, R34
S-phrases (S1/2), S9, S26, S28, S36/37/39, S45
Flash point Non-flammable
Related compounds
Related nitrogen oxides Nitrous oxide
Nitric oxide
Dinitrogen trioxide
Nitrogen dioxide
Dinitrogen pentoxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Dinitrogen tetroxide, also known as nitrogen tetroxide or dinitrogen tetraoxide, is a chemical compound. Its chemical formula is N2O4. It contains nitrogen in its +4 oxidation state. It contains nitrogen and oxide ions.

Properties[change | change source]

It is a colorless gas, although it is sometimes polluted with nitrogen dioxide. It is very corrosive and a strong oxidizing agent. It can ignite on contact with hydrazine. It can be made by bonding two nitrogen dioxide molecules together at a low temperature or a high pressure.

Preparation[change | change source]

It is made by bonding nitrogen dioxide molecules together in pairs.

Uses[change | change source]

It is used as a rocket propellant, along with hydrazine. This mixture is good since it does not have to be ignited. It is used similar to nitrogen dioxide to make nitric acid. It can react with metals to make nitrates.

Safety[change | change source]

Dinitrogen is highly toxic and corrosive. Some astronauts breathed it and had to go to a hospital.

Related pages[change | change source]

Sources[change | change source]

  1. International Chemical Safety Card
  2. 2.0 2.1 P.W. Atkins and J. de Paula, Physical Chemistry (8th ed., W.H. Freeman, 2006) p.999