Potassium+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]. Major uses of potassium nitrate are in fertilizers, [|food additive], [|rocket propellants] and [|fireworks] ; it is one of the constituents of [|gunpowder].
 * Potassium nitrate** is a [|chemical compound] with the [|formula] [|K][|N][|O] 3. It is an [|ionic salt] of [|potassium ions] K+ and [|nitrate ions] NO3−.

Potassium nitrates supplied the oxidant and much of the energy for gunpowder in the 19th century.

History
Potassium nitrate is a colorless solid. It dissolves in water. It is a common source of the nitrate ion. Potassium nitrate is a strong [|oxidizer]. It decomposes to potassium nitrite and oxygen when heated. Its [|pH] is almost neutral. It burns with a lilac flame. **Uses:**
 * The earliest known complete purification process for potassium nitrate was outlined in 1270 by the chemist and engineer Hasan al-Rammah of Syria
 * From 1903 until the World War I era, potassium nitrate for black powder and fertilizer was produced on an industrial scale from nitric acid produced via the Birkeland–Eyde process, which used an electric arc to oxidize nitrogen from the air.
 * Fertilizer
 * Oxidizer
 * Food Preservation
 * Toothpastes

Properties
Potassium nitrate has an orthorhombic crystal structure at room temperature, which transforms to a trigonal system at 129 °C. Upon heating to temperatures above 560 °C, it decomposes into potassium nitrite, generating oxygen: 2 KNO3 → 2 KNO2 + O2 Potassium nitrate is moderately soluble in water, but its solubility increases with temperature. The aqueous solution is almost neutral, exhibiting pH 6.2 at 14 °C for a 10% solution of commercial powder. It is not very hygroscopic, absorbing about 0.03% water in 80% relative humidity over 50 days. It is insoluble in alcohol and is not poisonous; it can react explosively with reducing agents, but it is not explosive on its own.

Oxidizer
Potassium nitrate is an efficient oxidizer, producing a lilac-colored flame upon burning due to the presence of potassium. It is one of the three components of black powder, along with powdered charcoal (substantially carbon) and sulfur, both of which act as fuels in this composition.As such it is used in black powder rocket motors, but also in combination with other fuels like sugars in "rocket candy". It is also used in fireworks such as smoke bombs, made with a mixture of sucrose and potassium nitrate.It is also added to pre-rolled cigarettes to maintain an even burn of the tobacco and is used to ensure complete combustion of paper cartridges for cap and ball revolvers.