Basic information Description Uses potassium nitrate fertilizer References Safety Supplier Related
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Potassium nitrate

Potassium nitrate (chemical formula: KNO3) is the nitrate of potassium. It is a crystalline salt and a strong oxidizer which can be specially used in making gunpowder, as a fertilizer, and in medicine. It can be manufactured through the reaction between ammonium nitrate and potassium hydroxide, and alternatively through the reaction between ammonium nitrate with potassium chloride.

Basic information Description Uses potassium nitrate fertilizer References Safety Supplier Related

Potassium nitrate Basic information

Product Name:
Potassium nitrate
  • nitre
  • vicknite
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Mol File:

Potassium nitrate Chemical Properties

Melting point:
334 °C (lit.)
Boiling point:
100 °C750 mm Hg
1.00 g/mL at 20 °C
Flash point:
storage temp. 
Store at RT.
H2O: 1 M at 20 °C, clear, colorless
Specific Gravity
5.0-7.5 (50g/l, H2O, 20℃)
Water Solubility 
320 g/L (20 ºC)
Stable. Strong oxidizer - contact with combustible material may cause fire. Incompatible with combustible materials, strong reducing agents.
CAS DataBase Reference
7757-79-1(CAS DataBase Reference)
EPA Substance Registry System
Potassium nitrate (7757-79-1)

Safety Information

Hazard Codes 
Risk Statements 
Safety Statements 
UN 3264 8/PG 3
WGK Germany 
HS Code 
2834 21 00
Hazardous Substances Data
7757-79-1(Hazardous Substances Data)
LD50 orally in rabbits: 1.166 g anion/kg, Dollahite, Rowe, Southwest. Vet. 27, 246 (1974)



Potassium nitrate Usage And Synthesis


Potassium nitrate (chemical formula: KNO3) is the nitrate of potassium. It is a crystalline salt and a strong oxidizer which can be specially used in making gunpowder, as a fertilizer, and in medicine. It can be manufactured through the reaction between ammonium nitrate and potassium hydroxide, and alternatively through the reaction between ammonium nitrate with potassium chloride. Potassium nitrate has various applications. Its major applications include: fertilizer, tree stump removal, rocket propellant and fireworks. It can also be used for the nitric acid production. It is also useful for food preservation and food preparation. In pharmacology, it can be used to treat asthma and relieving high blood pressure.


  1. Potassium nitrate is used chiefly in the manufacture of gunpowder or other explosives, but is also used for fireworks,for lucifer matches, for curing meat, for manufacture of certain kinds of glass, for flux in metallurgical assays, for some dyeing, and in medicine.
  2. In agriculture, potassium nitrate is used as a water-soluble and virtually chloride-free source of nitrate-nitrogen and potassium nutrients. Due to the product's specific characteristics and benefits, target markets are related to high-value crops such as vegetables, fruits and flowers. Furthermore, chloride-sensitive crops, such as potato, strawberry, beans, cabbage, lettuce, peanut, carrot, onion, blackberry tobacco, apricot, grapefruit and avocado, will depend for their quality on the use of chloride-free K sources, such as potassium nitrate.
  3. Potassium nitrate is used in a wide variety of applications including glass manufacturing, explosives for mining and civil works, metal treatment, fireworks, and recently, as a means to drastically increase the efficiency of Concentrating Solar Power (CSP) plants as described in the following paragraph.

potassium nitrate fertilizer

Potassium nitrate is a water-soluble NK fertilizer containing 13.7% nitrate nitrogen and 46% potassium oxide (38.4%). Potassium nitrate (KNO3) is a soluble source of two major essential plant nutrients. It’s commonly used as a fertilizer for high-value crops that benefit from nitrate (NO3-) nutrition and a source of potassium (K+) free of chloride (Cl-).
Manufacturers typically make potassium nitrate fertilizer (sometimes referred to as nitrate of potash or NOP by reacting potassium chloride (KCl) with a nitrate source. Depending on the objectives and available resources, the nitrate may come from sodium nitrate, nitric acid or ammonium nitrate. The resulting KNO3 is identical regardless of the manufacturing process. Potassium nitrate is commonly sold as a water-soluble, crystalline material primarily intended for dissolving and applying with water or in a prilled form for soil application. Traditionally, this compound is known as saltpeter.
Growers value fertilizing with KNO3 especially in conditions where a highly soluble, chloride-free nutrient source is needed. In such soils, all of the N is immediately available for plant uptake as nitrate, requiring no additional microbial action and soil transformation. Growers of high-value vegetable and orchard crops sometime prefer to use a nitrate-based source of nutrition in an effort to boost yield and quality. Potassium nitrate contains a relatively high proportion of K, with an N to K ratio of approximately one to three. Many crops have high K demands and can remove as much or more K than N at harvest. Applications of KNO3 to the soil are made before the growing season or as a supplement during the growing season. A diluted solution is sometimes sprayed on plant foliage to stimulate physiological processes or to overcome nutrient deficiencies. Foliar application of K during fruit development  advantages some crops, since this growth stage often coincides with high K demands during the time of declining root activity and nutrient uptake. It’s also commonly used for greenhouse plant production and hydroponic culture. Potassium nitrate accounts for only a small portion of the global K fertilizer market. It’s primarily used where its unique composition and properties can provide specific benefits to growers. Further, it’s easy to handle and apply, and is compatible with many other fertilizers, including specialty fertilizers for many high-value specialty crops, as well as those used on grain and fiber crops.




Potassium nitrate is a solid, colorless, crystalline ionic compound that exists as the mineral niter.Potassium nitrate is also known as saltpeter. The name saltpeter comes from the Latin sal petrae, meaning salt of stone or salt of Petra. he term saltpeter or Chilean saltpeter is also used for sodium nitrate, NaNO3.

Chemical Properties

Potassium nitrate is an odorless, flammable, water-soluble, white or colorless crystals with saline taste that melt at 337°C. Used in pyrotechnics, explosives, and matches, as a fertilizer, and as an analytical reagent.

Physical properties

Colorless transparent crystals or white granular or crystalline powder;rhombohedral structure; density 2.11 g/cm3at 20°C; melts at 334°C; decomposes at 400°C evolving oxygen; soluble in cold water, 13.3 g/100mL at 0°C;highly soluble in boiling water, 247 g/100mL at 100°C; lowers the temperature of water on dissolution; very slightly soluble in ethanol; soluble in glycerol and liquid ammonia.


Saltpeter’s most prominent use in human history is as the principal ingredient in gunpowder.The potassium nitrate used in gunpowder was originally obtained from natural mineral deposits of niter. Small quantities formed as efflorescence deposits on damp stone walls were identified as early as 2000 b.c.e. in Sumerian writings. As the use of black powder expanded with the development of weapons, the demand for saltpeter exceeded supply. This was exacerbated during times of war. To meet the demand for saltpeter to produce black powder, a saltpeter industry developed that followed prescribed methods to produce large quantities of saltpeter. The method depended on processing dirt obtained from areas where nitrates would naturally form. These were areas in which animal waste had accumulated such as the dirt floors of barns, stables, herding pens, caves, or cellars. The ammonia compounds in the urine and fecal wastes in these areas underwent nitrifi cation to produce nitrates, which combined with potassium in the soil to form saltpeter.


Although the most prominent use of saltpeter is for the production of black powder,potassium nitrate is also used as fertilizer. In the first half of the 17th century, JohannRudolf Glauber (1604–1668) obtained saltpeter from animal pens and discovered its useto promote plant growth. Glauber included saltpeter with other nutrients in fertilizer mixtures. Glauber’s work was one of the first to indicate the importance of nutrient cyclingin plant nutrition.


Potassium Nitrate is a preservative and color fixative in meats which exists as colorless prisms or white granules or powder. it has a solubility of 1 g in 3 ml of water at 25°c. see nitrate.


This natural substance is the product of the decomposition of lime and urine. The white granules or powder are soluble in water 1:3 but insoluble in alcohol. Potassium nitrate, also called saltpeter or nitre, was combined with sulfuric acid to nitrate cotton for the manufacture of collodion. It was also used with magnesium to make flash powder and added to ferrous sulfate developers to produced cool white tones in collodion positives.


In fireworks, fluxes, pickling meats; production of nitric acid; manufacture of glass, matches, gunpowder; freezing mixtures. Agricultural fertilizer. Preservative in foods. In dentrifices to reduce tooth hypersensitivity.


ChEBI: The inorganic nitrate salt of potassium.

Production Methods

Potassium nitrate may be produced by several methods. It is made commercially by reacting potassium chloride with nitric acid at high temperature.Nitrosyl chloride, a product obtained in the reaction, is converted into chlorine in this manufacturing process. Also, nitric acid is partly recycled in the process. The reactions are (Dancy, W.B. 1981. Potassium Compounds. In Kirk-Othmer Encyclopedia of Chemical Technology, 3rd. ed. Pp. 939-42. New York: Wiley Interscience):
3KCl + 4HNO3 →3KNO3+ Cl2+ NOCl + 2H2O
2NOCl + 4HNO3→6NO2+ Cl2+ 2H2O
4NO2+ O2+ 2H2O →4HNO3
Potassium nitrate also can be prepared by mixing a hot saturated solution of potassium chloride and sodium nitrate. The reaction is:
K++ Clˉ+ Na++ NO3ˉ→NaCl↓+ K++ NO3ˉ
Sodium chloride is less soluble than KCl, NaNo3and KNo3. It separates out by crystallization. The remaining solution is cooled to ambient tempera-ture. Potassium nitrate crystallizes out.

brand name

Cholal modifico;Cholal simple;Dewitt's pills for backache and joint pain;Viridite k.

World Health Organization (WHO)

Potassium nitrate was formerly used as a diuretic. Its use for this purpose is now considered obsolete but it is still available in at least one country for the correction of potassium deficiency. It is aslo widely permitted at concentrations of the order of 5% in proprietary toothpastes. In some countries the drug has been banned due to a potential carcinogenic risk arising from the excessive use of nitrates and their transformation to nitrosamines.

General Description

A white to dirty gray crystalline solid. Water soluble. Noncombustible, but accelerates the burning of combustible materials. If large quantities are involved in fire or the combustible material is finely divided an explosion may result. May explode under prolonged exposure to heat or fire. Toxic oxides of nitrogen are produced in fires. Used in solid propellants, explosives, fertilizers.

Air & Water Reactions

Soluble in water.

Reactivity Profile

Potassium nitrate mixed with alkyl esters may explode, owing to the formation of alkyl nitrates; mixtures with phosphorus, tin (II) chloride, or other reducing agents may react explosively [Bretherick 1979. p. 108-109]. Powdered antimony mixed with Potassium nitrate explodes when heated [Mellor 9:282 1946-47]. A mixture of antimony trisulfide and Potassium nitrate explodes at a red heat [Mellor 9:524. 1946-47]. Arsenic disulfide forms explosive mixtures when mixed with Potassium nitrate, [Mellor 9:270.1946-47]. A mixture of sodium acetate and Potassium nitrate may cause an explosion [Pieters 1957. p. 30]. A mixture of Potassium nitrate and sodium hypophosphite constitutes a powerful explosive [Mellor 8:881. 1946-47]. A mixture of powdered zirconium and Potassium nitrate explodes when heated above the melting point [Mellor 7:116. 1946-47].


Dangerous fire and explosion risk when shocked or heated, or in contact with organic mate- rials, strong oxidizing agent.

Health Hazard

Exposure can cause mild irritation of eyes, nose and throat.

Flammability and Explosibility


Agricultural Uses

Potassium nitrate (KNO3) is a potassium salt of nitric acid, also known as saltpeter or nitrate of potash. It is a white crystalline salt which occurs naturally in nitre or saltpeter. It can be used as fertilizer for normal application and fertigation. Potassium (44% K2O) and nitrogen (13 %) are the constituents of NK fertilizers, which serve as a source of potassium, where extra chloride is not desired.
The agricultural grade of potassium nitrate is freeflowing and non-caking, with a particle size in the range of 1500 to 400 microns.
Potassium nitrate, which is slightly hygroscopic and granulated, can be spread on soil by trucks, fertilizer distributors or by aerial spraying. In a mixed fertilizer, a powdered grade of nitrate of potash does not cake. Potassium nitrate is made by the reaction of potassium chloride with nitric acid as: The nitrate of potash forms an easily breakable crust on top. It is chemically neutral and its nitrogen and potassium oxide ratio is roughly 1:3. It has been used successfully as a source of nitrogen and potassium for tobacco, tomato, potato, corn, citrus and carnations.

Industrial uses

Potassium nitrate is also called niter and saltpeter,although these usually refer to the nativemineral. A substance of the composition KNO3,it is used in explosives, for bluing steel, and infertilizers. A mixture of potassium nitrate andsodium nitrate is used for steel-tempering baths.The mixture melts at 250°C. Potassium nitrateis made by the action of potassium chloride onsodium nitrate. It occurs in colorless prismaticcrystals, or as a crystalline white powder. It hasa sharp saline taste and is soluble in water. Thespecific gravity is 2.1 and the melting point is337°C.
Potassium nitrate contains a large percentageof oxygen, which is readily given up andis well adapted for pyrotechnic compounds. Itgives a beautiful violet flame in burning. It isused in flares and in signal rockets.
Most enamels contain some oxidizing agentin the form of potassium or sodium nitrate.Only a small amount of nitrate is necessary; 2to 4% is sufficient to maintain oxidizing conditionsin most smelting operations.
In glazes it is sometimes used as a flux inplace of potassium oxide, but, owing to its costand solubility, very little of it is contained inglaze. Where conditions prevent the use of sufficientpotash feldspar, potassium oxide is introducedinto the mix, usually in the form of thenitrate in a frit.
Potassium nitrite is a solid of the compositionKNO2 used as a rust inhibitor, for theregeneration of heat-transfer salts, and for themanufacture of dyes.

Biochem/physiol Actions

Potassium nitrate serves as a source of nitrate for cell growth. It also induces the synthesis of lipid in alga Neochloris oleoabundans.

Safety Profile

Poison by intravenous route. Moderately toxic by ingestion. An experimental teratogen. Experimental reproductive effects. Mutation data reported. Ingestion of large quantities may cause gastroenteritis. Chronic exposure can cause anemia, nephritis, and methemoglobinemia. When heated, reaction with calcium hydroxide + polychlorinated phenols forms extremely toxic chlorinated benzodtoxins. A powerful oxidizer. Gunpowder is a mixture of potassium nitrate + sulfur + charcoal. Explosive reaction with aluminum + barium nitrate + potassium perchlorate + water (in storage), boron + laminac + trichloroethylene. Forms explosive mixtures with lactose, powdered metals (e.g., titanium, antimony, germanium), metal sulfides (e.g., antimony trisulfide, barium sulfide, calcium sulfide, germanium monosulfide, titanium disulfide, arsenic disulfide, molybdenum disulfide), nonmetals (e.g., boron, carbon, white phosphorus, arsenic), organic materials, phosphides (e.g., copper(l1) phosphide, copper monophosphide), reducing agents (e.g., sodium phosphinate, sodium thiosulfate), sodium acetate. Can react violently under the appropriate conditions with 1,3- bis(trichlorometh~d)benzene, boron phosphde, F2, calcium shcide, charcoal, chromium nitride, Na hypophosphte, ma2O2 + dextrose), red phosphorus, (S + As2S3), thorium dicarbide, trichloroethylene, zinc, zirconium. When heated to decomposition it emits very toxic fumes of NOx and K2O. See also NITRATES.

Potential Exposure

Used to make explosives, gunpowder, fireworks, rocket fuel; matches, fertilizer, fluxes, glass manufacture; and as a diuretic


UN1486 Potassium nitrate, Hazard Class: 5.1; Labels: 5.1-Oxidizer.

Purification Methods

It crystallises from hot H2O (0.5mL/g) on cooling (cf KNO2 below). Dry it for 12hours under vacuum at 70o. The solubility in H2O is 13.3% at 0o, 110% at 60o, and 246% at 100o. After two recrystallisations, technical grade salt had <0.001 ppm of metals. The fused salt is a powerful oxidising agent.


A powerful oxidizer. Dangerously reactive and friction-and shock-sensitive when mixed with organic materials and many materials. Violent reactions with reducing agents; chemically active metals; charcoal, trichloroethylene.

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