Potassium Nitrate Overview

Potassium nitrate is a chemical compound with the chemical formula KNO3. A naturally occurring mineral source of nitrogen, KNO3 constitutes a critical oxidizing component of black powder gunpowder. In the past it was also used for several kinds of burning fuses, including slow matches.

Since potassium nitrate readily precipitates, urine was a significant source, through various malodorous means, from the Late Middle Ages and Early Modern era through the 19th century.

Its common names include saltpeter (from Medieval Latin sal petrae: “stone salt” or possibly “Salt of Petra”), American English saltpeter, Nitrate of potash, and nitre. The name Chile saltpeter is also applied to sodium nitrate, which, though also used in explosives and fertilizers, is a very different compound.

Description

Potassium nitrate is the oxidizing component of black powder. Before the large-scale industrial fixation of nitrogen through the Haber process, major sources of potassium nitrate were the deposits crystallizing from cave walls and the draining of decomposing organic material. Dung-heaps were a particularly common source: ammonia from the decomposition of urea and other nitrogenous materials would undergo bacterial oxidation to produce nitrate.

It was and is also used as a component in some fertilizers. When used by itself as a fertilizer, it has an NPK rating of 13-0-44 (indicating 13%, 0%, and 44% of nitrogen, phosphorus, and potassium, by mass, respectively). Potassium nitrate was once thought to induce impotence, and is still rumored to be in institutional food (such as military fare) as an anaphrodisiac. However, these uses would be ineffective, since potassium nitrate has no such properties.

Potassium nitrate is also used as a fertilizer, in amateur rocket propellant, and in several fireworks such as smoke bombs, in which a mixture with sugar produces a smoke cloud of 600 times their own volume. The ratio for smoke bombs using sucrose (powdered sugar) and potassium nitrate is 40(C12H22O11):60(KNO3). It can be used as is, or carefully melted together using a hot plate.

It has also been used in the manufacture of ice cream and can be found in some toothpastes for sensitive teeth.] Recently, the use of potassium nitrate in toothpastes for treating sensitive teeth has increased dramatically, despite the fact that it has not been conclusively shown to help dental hypersensitivity.

Potassium nitrate is also one of the three parts of black powder, along with powdered charcoal (substantially carbon) and sulfur.[citation needed] It acts as an oxidizer, oxidizing the carbon and sulfur to their respective oxides.

PRODUCT IDENTIFICATION
CAS NO. 7757-79-1
EINECS NO. 231-818-8
FORMULA KNO3
MOL WT. 101.1

H.S. CODE

2834.21
TOXICITY Oral rat LD50: 3750 mg/kg
SYNONYMS
Nitre;Nitric Acid Potassium Salt; Saltpeter; Vicknite;Kalii Nitras; Kaliumnitrat (German); Niter; Nitrate Of Potash;
PHYSICAL AND CHEMICAL PROPERTIES
PHYSICAL STATE odorless white crystals
MELTING POINT

334 C

BOILING POINT (Decomposes at 400 C)
SPECIFIC GRAVITY 2.11
SOLUBILITY IN WATER soluble
VAPOR DENSITY 3.0
NFPA RATINGS Health: 2; Flammability: 0; Reactivity: 0 Special Hazard: OX
FLASH POINT Not combustible, but substance is a strong oxidizer
STABILITY Stable under ordinary conditions
SALES SPECIFICATION
APPEARANCE white powder
ASSAY (as KNO3) 99.5% min
POTASSIUM OXIDE (as K2O ) 46.0% min
NITROGEN 13.0% min
MOISTURE 0.1% max
WATER INSOLUBLES 0.02% max
SUIPHATE (as SO4) 0.01% max
CHLORIDE (as Cl) 0.03% max
IRON(as Fe) 0.002% max
NITRITES 0.01% max
HEAVY METAL (as Pb) 0.001% max
PARTICLE SIZE 100% -20 mesh, 95% +200 mesh