Nitric oxide

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Nitric oxide
Names
IUPAC name
Nitric oxide
Other names
Mononitrogen monoxide
Nitrogen monooxide
Nitrogen monoxide
Nitrogen(II) oxide
Nitrosyl
Oxidonitrogen
Properties
NO
Molar mass 30.01 g/mol
Appearance Colorless gas
Odor Sharp, sweet
Density 1.3402 g/cm3
Melting point −164 °C (−263 °F; 109 K)
Boiling point −152 °C (−242 °F; 121 K)
0.0098 g/100 ml (0 °C)
0.0056 g/100 ml (20 °C)
Solubility Soluble in carbon disulfide
Solubility in ethanol 26.6 ml/100 ml
Solubility in sulfuric acid 3.4 ml/100 ml
Vapor pressure 26000 mmHg at 20 °C
Thermochemistry
210.76 J·K−1·mol−1
91.29 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
315 ppm (rabbit, 15 min)
854 ppm (rat, 4 hr)
320 ppm (mouse)
Related compounds
Related compounds
Nitrous oxide
Nitrogen dioxide
Dinitrogen trioxide
Dinitrogen tetroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Nitric oxide (also known as nitrogen oxide or nitrogen monoxide) is a molecular, chemical compound with chemical formula of ·NO (also written as ·NO). Nitric oxide is a free radical—i.e., its bonding structure includes an unpaired electron, represented by the dot (·) on the nitrogen atom.

Properties

Chemical

Nitric oxide oxidizes in air to give nitrogen dioxide.

NO + ½ O2 → NO2

Nitric oxide can also react directly with sodium methoxide, forming sodium formate and nitrous oxide.

Physical

Nitric oxide is a colorless gas, almost insoluble in water.

Availability

Nitric oxide is sold by chemical suppliers in gas cylinders, though it's difficult for the amateur chemist to acquire this compound.

Preparation

Nitric oxide is industrially produced by the oxidation of ammonia at 750–900 °C (usually at 850 °C) with platinum as catalyst:

4 NH3 + 5 O2 → 4 ·NO + 6 H2O

A more accessible route involves the reduction of dilute nitric acid with copper:

8 HNO3 + 3 Cu → 3 Cu(NO3)2 + 4 H2O + 2 ·NO

If this reaction occurs in the presence of air, the resulting nitric acid will react with oxygen to give the brown nitrogen dioxide. If concentrated nitric acid is used, nitrogen dioxide will also be formed as side product.

Other routes to this compound involve sodium nitrite or potassium nitrite:

2 NaNO2 + 2 NaI + 2 H2SO4 → I2 + 4 NaHSO4 + 2 ·NO
2 NaNO2 + 2 FeSO4 + 3 H2SO4 → Fe2(SO4)3 + 2 NaHSO4 + 2 H2O + 2 ·NO
3 KNO2(l) + KNO3(l) + Cr2O3(s) → 2 K2CrO4(s) + 4 NO(g)

Projects

  • Make nitrous oxide
  • Make metal nitrosyls

Handling

Safety

Nitric oxide will convert to nitrogen dioxide when exposed to air.

Storage

Nitric oxide tanks should be kept in a cold place, away from light and heat.

Disposal

Can be neutralized by bubbling it in a sodium percarbonate solution.

References

Relevant Sciencemadness threads