Saltpetre

Potassium nitrate

Names
IUPAC name Potassium nitrate
Other names Saltpetre Nitrate of potash
Identifiers
CAS Number	7757-79-1 Y
3D model (Jmol)	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	24434
RTECS number	TT3700000
UNII	RU45X2JN0Z Y
UN number	1486
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	decomposes at 400 °C
Solubility in water	133 g/L (0 °C) 316 g/L (20 °C) 2460 g/L (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
Specific heat capacity (C)	95.06 J/mol K
Std enthalpy of formation (ΔfHo298)	-494.00 kJ/mol
Hazards
Main hazards	Oxidant, Harmful if swallowed, Inhaled, or absorbed on skin. Causes Irritation to Skin and Eye area.
Safety data sheet	See: data page ICSC 0184
EU classification (DSD)	Oxidant (O)
R-phrases	R8 R22 R36 R37 R38
S-phrases	S7 S16 S17 S26 S36 S41
NFPA 704	0 1 0 OX
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1901 mg/kg (oral, rabbit) 3750 mg/kg (oral, rat)
Related compounds
Other anions	Potassium nitrite
Other cations	Lithium nitrate Sodium nitrate Rubidium nitrate Caesium nitrate
Related compounds	Potassium sulfate Potassium chloride
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
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

Potassium nitrate is a chemical compound with the chemical formula KNO₃. It is an ionic salt of potassium ions K⁺ and nitrate ions NO₃⁻, and is therefore an alkali metal nitrate.

It occurs as a mineral niter and is a natural solid source of nitrogen. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpeter or saltpetre.

Major uses of potassium nitrate are in fertilizers, tree stump removal, rocket propellants and fireworks. It is one of the major constituents of gunpowder (blackpowder) and has been used since the Middle Ages as a food preservative.

Potassium nitrate, because of its early and global use and production, has many names.

The Greeks used the term nitron, which was Latinised to nitrum or nitrium, while earlier Hebrews and Egyptians used words with the consonants n-t-r, which leads some to speculate that the Latin term is closer to the original than the Greek term. Middle English styled it nitre. Old French had niter. By the 15th century, Europeans referred to it as saltpeter and later as nitrate of potash, as the chemistry of the compound was more fully understood.

The Arabs called it "Chinese snow" (Arabic: ثلج الصين‎‎ thalj al-ṣīn). It was called "Chinese salt" by the Iranians/Persians or "salt from Chinese salt marshes" (Persian: نمک شوره چيني‎‎ namak shūra chīnī).