Dinitrogen trioxide

Dinitrogen trioxide

N2O3 droplets in glass ampoule
Names
IUPAC name Dinitrogen trioxide
Preferred IUPAC name Dinitrogen trioxide
Other names N-oxonitramide Nitrogen sesquioxide Nitrous anhydride
Identifiers
Jmol-3D images	Image
SMILES N(=O)[N+](=O)[O-]
Properties
Chemical formula	N2O3
Molar mass	76.01 g/mol
Appearance	Deep blue gas
Odor	Stinging, unpleasant
Density	1.447 g/cm3 (liquid) 1.783 g/cm3 (gas)
Melting point	−100.7 °C (−149.3 °F; 172.5 K)
Boiling point	3.5 °C (38.3 °F; 276.6 K) (dissociates)
Solubility in water	Reacts
Solubility	Reacts with alcohols Soluble in CCl4, chloroform, diethyl ether, sulfuryl chloride, liq. xenon
Thermochemistry
Std molar entropy (So298)	314.63 J·K-1·mol-1
Std enthalpy of formation (ΔfHo298)	91.20 kJ/mol
Hazards
Safety data sheet	None
Flash point	Non-flammable
Related compounds
Related compounds	Nitrous oxide Nitric oxide Nitrogen dioxide Dinitrogen tetroxide Dinitrogen pentoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Dinitrogen trioxide is a chemical compound with the chemical formula N₂O₃.

Properties

Chemical

It is the anhydride of the unstable nitrous acid (HNO₂) and produces it when mixed into water.

N₂O₃ + 2 H₂O → 2 HNO₂

If the nitrous acid is not then used up quickly, it decomposes into nitric oxide and nitric acid. Nitrite salts are sometimes produced by adding N₂O₃ to alkaline solutions:

N₂O₃ + 2 NaOH → 2 NaNO₂ + H₂O

Physical

Dinitrogen trioxide is a blue gas, with a strong odor.

Availability

This compound is not sold and has to be made in situ.

Preparation

Can be prepared by mixing equal parts of nitric oxide and nitrogen dioxide and cooling the mixture below -21 °C. Toluene can be used as solvent. Yield is given as 94.4 %.

NO + NO₂ ⇌ N₂O₃

Both gasses can be obtained by dissolving copper in conc. nitric acid.

An older route involves the oxidation of nitric oxide with pure oxygen, in neat, at -54 °C.

2 NO + ½ O₂ ⇌ N₂O₃

Dinitrogen trioxide is only isolable at low temperatures, i.e. in the liquid and solid phases. At higher temperatures the equilibrium favors the constituent gases, with K_diss = 193 kPa (25 °C).

Projects

• Make very pure nitrous acid
• Make nitrites
• Compound collecting

Handling

Safety

Dinitrogen trioxide is toxic and corrosive.

Storage

Can only be kept at very low temperatures, but not for long.

Disposal

Can be neutralized by bubbling it in alkaline water.

Gallery

• 

  Another view of the N₂O₃ sample

References

Relevant Sciencemadness threads

• Possible urgent scenario regarding the ampuling of nitrogen oxides