Potassium nitrate

Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula KNO₃. It is a potassium salt of nitric acid. This salt consists of potassium cations K⁺ and nitrate anions NO−3, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter (or nitre outside the US). It is a source of nitrogen, and nitrogen was named after niter. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpetre (or saltpeter in the US).

Potassium nitrate

Names
IUPAC name Potassium nitrate
Other names Saltpeter Saltpetre Nitrate of potash
Identifiers
CAS Number	7757-79-1 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1644029 N
ChemSpider	22843 Y
ECHA InfoCard	100.028.926
EC Number	231-818-8
E number	E252 (preservatives)
KEGG	D02051 Y
PubChem CID	24434
RTECS number	TT3700000
UNII	RU45X2JN0Z Y
UN number	1486
CompTox Dashboard (EPA)	DTXSID4029692
InChI InChI=1S/K.NO3/c;2-1(3)4/q+1;-1 Y Key: FGIUAXJPYTZDNR-UHFFFAOYSA-N Y InChI=1/K.NO3/c;2-1(3)4/q+1;-1 Key: FGIUAXJPYTZDNR-UHFFFAOYAM
SMILES [K+].[O-][N+]([O-])=O
Properties
Chemical formula	KNO3
Molar mass	101.1032 g/mol
Appearance	white solid
Odor	odorless
Density	2.109 g/cm3 (16 °C)
Melting point	334 °C (633 °F; 607 K)
Boiling point	400 °C (752 °F; 673 K) (decomposes)
Solubility in water	133 g/(1000 g) (0 °C) 316 g/(1000 g) (20 °C) 383 g/(1000 g) (25 °C) 2439 g/(1000 g) (100 °C)
Solubility	slightly soluble in ethanol soluble in glycerol, ammonia
Basicity (pKb)	15.3
Magnetic susceptibility (χ)	−33.7·10−6 cm3/mol
Refractive index (nD)	1.335, 1.5056, 1.5604
Structure
Crystal structure	Orthorhombic, Aragonite
Thermochemistry
Heat capacity (C)	95.06 J/mol K
Std enthalpy of formation (ΔfH⦵298)	−494.00 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Oxidant, harmful if swallowed, inhaled, or absorbed on skin. Causes irritation to skin and eye area.
GHS labelling:
Pictograms
Hazard statements	H272, H315, H319, H335
Precautionary statements	P102, P210, P220, P221, P280
NFPA 704 (fire diamond)	1 0 0 OX
Flash point	non-flammable (oxidizer)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1901 mg/kg (oral, rabbit) 3750 mg/kg (oral, rat)
Safety data sheet (SDS)	ICSC 0184
Related compounds
Other anions	Potassium nitrite
Other cations	Lithium nitrate Sodium nitrate Rubidium nitrate Caesium nitrate Ammonium nitrate Silver nitrate Calcium nitrate
Related compounds	Potassium sulfate Potassium chloride
Supplementary data page
Potassium nitrate (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Major uses of potassium nitrate are in fertilizers, tree stump removal, rocket propellants and fireworks. It is one of the major constituents of traditional gunpowder (black powder). In processed meats, potassium nitrate reacts with hemoglobin and myoglobin generating a red color, becoming highly toxic and carcinogenic.