Nitric oxide
| Names | |
|---|---|
| IUPAC name
Nitric oxide
| |
| Other names
Mononitrogen monoxide
Nitrogen monooxide Nitrogen monoxide Nitrogen(II) oxide Nitrosyl Oxidonitrogen | |
| Properties | |
| NO or ·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, ethanol |
| 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 | |
| Std molar
entropy (S |
210.76 J·K−1·mol−1 |
| Std enthalpy of
formation (ΔfH |
91.29 kJ/mol |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Flash point | Non-flammable |
| Lethal dose or concentration (LD, LC): | |
| LC50 (Median concentration)
|
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 or •NO). Nitric oxide is a free radical—i.e., its bonding structure includes an unpaired electron, represented by the dot (·) on the nitrogen atom.
Contents
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, which is highly toxic and corrosive, and will turn into nitric acid upon contact with moisture.
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.
