Nitrogen(II) oxide

Nitric oxide

Names
IUPAC name Nitric oxide
Systematic IUPAC name Oxidonitrogen(•) (additive)
Other names Nitrogen monoxide Nitrogen(II) oxide
Identifiers
CAS Number	10102-43-9 Y
3D model (JSmol)	Interactive image
3DMet	B00122
ChEBI	CHEBI:16480 Y
ChemSpider	127983 Y
DrugBank	DB00435 Y
ECHA InfoCard	100.030.233
EC Number	233-271-0
Gmelin Reference	451
IUPHAR/BPS	2509
KEGG	D00074 Y
PubChem CID	145068
RTECS number	QX0525000
UNII	31C4KY9ESH Y
UN number	1660
InChI InChI=1S/NO/c1-2 Y Key: MWUXSHHQAYIFBG-UHFFFAOYSA-N Y InChI=1/NO/c1-2 Key: MWUXSHHQAYIFBG-UHFFFAOYAI
SMILES [N]=O
Properties
Chemical formula	NO
Molar mass	30.01 g·mol−1
Appearance	Colourless gas
Density	1.3402 g dm−3
Melting point	−164 °C (−263 °F; 109 K)
Boiling point	−152 °C (−242 °F; 121 K)
Solubility in water	0.0098 g/100ml (0 °C) 0.0056 g/100ml (20 °C)
Refractive index (nD)	1.0002697
Structure
Molecular shape	linear (point group C∞v)
Thermochemistry
Std molar entropy (So298)	210.76 J K−1 mol−1
Std enthalpy of formation (ΔfHo298)	91.29 kJ mol−1
Pharmacology
ATC code	R07AX01 (WHO)
Routes of administration	Inhalation
Pharmacokinetics:
Bioavailability	good
Metabolism	via pulmonary capillary bed
Biological half-life	2–6 seconds
Hazards
Safety data sheet	External MSDS
EU classification (DSD) (outdated)	O T
R-phrases (outdated)	R8, R23, R34, R44
S-phrases (outdated)	(S1), S17, S23, S36/37/39, S45
NFPA 704	0 3 3 OX
Lethal dose or concentration (LD, LC):
LC50 (median concentration)	315 ppm (rabbit, 15 min) 854 ppm (rat, 4 hr) 320 ppm (mouse)
LCLo (lowest published)	2500 ppm (mouse, 12 min)
Related compounds
Related nitrogen oxides	Dinitrogen pentoxide Dinitrogen tetroxide Dinitrogen trioxide Nitrogen dioxide Nitrous oxide Nitroxyl (reduced form) Hydroxylamine (hydrogenated form)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Dinitrogen tetroxide
Dinitrogen trioxide
Nitrogen dioxide
Nitrous oxide
Nitroxyl (reduced form)
Hydroxylamine (hydrogenated form)

Nitric oxide (nitrogen oxide, nitrogen monoxide) is a molecular, chemical compound with chemical formula of ·NO. One of several oxides of nitrogen, it is a colorless gas under standard conditions. Nitric oxide is a free radical—i.e., its bonding structure includes an unpaired electron, represented by the dot (·) on the nitrogen atom—and it is in the class of heteronuclear diatomic molecules that are of historic theoretical interest (for the insights they gave in formulating early modern theories of bonding). It is a particularly important intermediate in the chemical industry. In addition, some is unavoidably produced during combustion of fossil fuels in power plants and automobile engines, with excess being created when more air or higher temperatures are present than needed for efficient and complete combustion of the fuel. It is also produced naturally by the extremely high air temperatures produced along the path of lightning in thunderstorms.