Saltpeter

2D structure of saltpeter.

Potassium nitrate sample

a piece of niter collected in Tarapaca, Chile

Potassium nitrate, also known as saltpeter, 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 is a source of nitrogen and it occurs in nature as a mineral, niter.

Production

Mineral Sources

Saltpeter minerals can be found in collected mineral deposits, and purified into usable saltpeter

Potassium Hydroxide & Nitric Acid

Potassium hydroxide or potassium carbonate can be used to neutralize nitric acid, producing aqueous potassium nitrate in the reactions shown below. Be sure to perform the reactions slowly and/or with temperature control, as they are highly exothermic.

KOH + HNO₃ → KNO₃ + H₂O

K₂CO₃ + 2 HNO₃ → 2 KNO₃ + H₂O + CO₂

Bacterial Oxidation

Certain strains of aerobic bacteria are capable of oxidizing some nitrogen-containing molecules to nitrates. Urea (found in urine) and ammonia are common biological sources of oxidizable nitrogen. Historically, potassium nitrate was produced on scale in niter beds by using naturally occurring bacteria to oxidize nitrogen-rich animal waste into nitrates which were then recovered through solvent extraction and recrystallization with water and hardwood ash. Bacterial oxidation is the primary mechanism which forms natural deposits.

Bat Guano

Bat guano is often rich in nitrates due to the bat's diet and bacterial oxidation. Nitrate can be extracted from bat guano in a similar manner to niter bed material.

Uses

Major uses of potassium nitrate are in fertilizers, tree stump removal, rocket propellants and fireworks, and it is one of the major components of gunpowder.

Dependencies

• Potassium
• Nitrogen
• Oxygen
  • Potassium nitrate
    • Gunpowder

See also

• Fertilizer
• Chemical compounds

References

This article uses material from the Wikipedia article Potassium_nitrate, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors).

This article uses material from the Wikipedia article Niter, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors).