Dinitrogen tetroxide

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.

Dinitrogen tetroxide

Full structural formula Space-filling model
Names
IUPAC name Dinitrogen tetraoxide
Other names Dinitrogen(II) oxide(-I)
Identifiers
CAS Number	10544-72-6
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29803
ChemSpider	23681
ECHA InfoCard	100.031.012
EC Number	234-126-4
PubChem CID	25352
RTECS number	QW9800000
UN number	1067
CompTox Dashboard (EPA)	DTXSID00893116
SMILES [O-] [N+](=O)[N+]([O-])=O
Properties
Chemical 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 (11.8 °F; 261.9 K)
Boiling point	21.69 °C (71.04 °F; 294.84 K)
Solubility in water	reacts
Vapor pressure	96 kPa (20 °C)[1]
Refractive index (nD)	1.00112
Structure
Molecular shape	planar, D2h
Dipole moment	zero
Thermochemistry
Std enthalpy of formation ΔfHo298	+9.16 kJ/mol[2]
Standard molar entropy So298	304.29 J K−1 mol−1[2]
Hazards
MSDS	External MSDS
EU classification	Very toxic (T+) Corrosive (C)
EU Index	007-002-00-0
NFPA 704	0 3 0 OX
R-phrases	R26, R34
S-phrases	(S1/2), S9, S26, S28, S36/37/39, S45
Flash point	Non-flammable
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Properties

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

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

Uses

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

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

Related pages

• Nitrous oxide
• Nitrogen oxide
• List of nitrogen compounds