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Potassium Chlorate
The structure of the ions in potassium chlorate
The crystal structure of potassium chlorate
Other names Potassium chlorate(V), Potcrate
CAS number 3811-04-9 Yes check.svgY
PubChem 6426889
EC number 223-289-7
UN number 1485
RTECS number FO0350000
Molecular formula KClO3
Molar mass 122.55 g/mol
Appearance White crystals or powder
Density 2.34 g/cm3
Melting point

356 °C

Boiling point

400 °C decomp.

Solubility in water 7.19 g/100 ml (20 °C)
57 g/100 mL (100 °C)
Solubility insoluble in acetone, liquid ammonia
Refractive index (nD) 1.40835
Crystal structure monoclinic
EU Index 017-004-00-3
EU classification Oxidant (O)
Harmful (Xn)
Dangerous for the environment (N)
R-phrases R9, R22, R51/53
S-phrases (S2), S13, S16, S27, S61
NFPA 704
NFPA 704.svg
Flash point 400 °C
LD50 1870 mg/kg
Related compounds
Other anions Potassium bromate
Potassium iodate
Other cations Ammonium chlorate
Sodium chlorate
Barium chlorate
Related compounds Potassium chloride
Potassium hypochlorite
Potassium chlorite
Potassium perchlorate
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Potassium chlorate is a compound containing potassium, chlorine and oxygen, with the molecular formula KClO3. In pure form, it is a white crystalline substance. It is the most common chlorate in industrial use, and is usually present in well-stocked laboratories. It is used



Potassium chlorate burning sugar

Potassium chlorate was one key ingredient in early firearms percussion caps (primers). It continues in that application, where not supplanted by potassium perchlorate.

Chlorate-based propellants are more efficient than traditional gunpowder and are less susceptible to damage by water. However, they can be extremely unstable in the presence of sulfur or phosphorus and are much more expensive. Chlorate propellants must be used only in equipment designed for them; failure to follow this precaution is a common source of accidents. Potassium chlorate, often in combination with silver fulminate, is used in trick noise-makers known as "crackers", "snappers", "pop-its", or "bang-snaps", a popular type of novelty firework.

When mixed with a suitable fuel, it may form an explosive material, a so-called Sprengel explosive. The hygroscopic and slightly weaker sodium chlorate is sometimes used as a safer and less expensive substitute for potassium chlorate. In World War I, mixes of potassium chlorate with plasticizers (such as wax) were the most common type of plastic explosive used, often filling grenades and other munitions. When used in explosives as an oxidizer, the explosive is low order meaning it burns rapidly rather than explodes. When mixed with a plasticizer, it may become high order, requiring a blasting cap (generally a commercial #8) to detonate properly. Potassium chlorate is also used in some formulas of gunpowder, generally replacing the less powerful potassium nitrate.

Potassium chlorate is often used in high school and college laboratories to generate oxygen gas; it is a far cheaper source than a pressurized or cryogenic oxygen tank. Potassium chlorate will readily decompose if heated in contact with a catalyst, typically manganese (IV) dioxide (MnO2). Thus, it may be simply placed in a test tube and heated over a burner. If the test tube is equipped with a one-holed stopper and hose, warm oxygen can be drawn off. The reaction is as follows:

2KClO3(s) + heat → 3O2(g) + 2KCl(s)

The safe performance of this reaction requires very pure reagents and careful temperature control. Molten potassium chlorate is an extremely powerful oxidizer and will spontaneously react with many common materials. Explosions have resulted from liquid chlorates spattering into the latex or PVC tubes of oxygen generators, as well as from contact between chlorates and hydrocarbon sealing greases. Impurities in potassium chlorate itself can also cause problems. When working with a new batch of potassium chlorate, it is advisable to take a small sample (~ 1 gram) and heat it strongly on an open glass plate. Contamination may cause this small quantity to explode, indicating that the chlorate should be discarded.

Potassium chlorate is used in chemical oxygen generators (also called chlorate candles or oxygen candles), employed as oxygen-supply systems of e.g. aircraft, space stations, and submarines, and has been responsible for at least one plane crash. A fire on the space station Mir was also traced to this substance. The decomposition of potassium chlorate was also used to provide the oxygen supply for limelights.

Potassium chlorate is used also as a pesticide. In Finland it was sold under trade name Fegabit.


Potassium chlorate should be handled with care. It reacts vigorously, and in some cases spontaneously ignites or explodes, when mixed with many combustible materials. It will burn vigorously in combination with virtually any combustible material, even those which are considered to by only slightly flammable normally (including ordinary dust and lint). Mixtures of potassium chlorate and a fuel can be ignited by contact with sulfuric acid and this reagent should be kept away from potassium chlorate. Sulfur should be avoided in pyrotechnic compositions containing potassium chlorate, as these mixtures are prone to spontaneous deflagration. Most sulfur contains trace quantities of sulfur-containing acids, and these can cause spontaneous ignition - "Flowers of sulfur" or "sublimed sulfur", despite the overall high purity, contains significant amounts of sulfur acids. Also, mixtures of potassium chlorate with any compound with ignition promoting properties (ex. antimony(III) sulfide) are very dangerous to prepare, as they are extremely shock sensitive.


On an industrial scale, potassium chlorate is produced by the electrolysis of a sodium chloride solution to form sodium chlorate, which is reacted with potassium chloride to precipitate potassium chlorate. The resultant sodium chloride is returned to the mother liquor for electrolysis.

KClO3 can also be produced on a smaller scale by the thermal disproportionation of a hypochlorite to its respective chlorate and chloride by boiling, then adding KCl. This reaction should be done in a fume hood due to the production of chlorine and chlorine dioxide gas.

See also


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Simple English

Potassium chlorate

Potassium chlorate is a chemical compound. Its chemical formula is KClO3. It has potassium and chlorate ions.



It is a colorless crystalline solid. It dissolves in water. It is a strong oxidizing agent. It gives off oxygen when heated. Sometimes manganese(IV) oxide is used to make the oxygen come faster. It can explode when mixed with a strong reducing agent. It can make many things burn that don't normally burn.


It is made by electrolysis of a hot solution of potassium chloride. This is similar to the chloralkali process. It can also be made by reacting concentrated sodium chlorate with potassium chloride.


It is used in fireworks. It is a part of Armstrong's mixture, a sensitive explosive. It is also used to make oxygen gas in high school and college labs. It can burn sugar when mixed with sugar and concentrated sulfuric acid. It can also replace potassium nitrate in gunpowder. It is used in oxygen candles. Oxygen candles made oxygen when burned. They are used in spaceships.


Potassium chlorate is a strong oxidizing agent and can catch many things on fire. When it is mixed with sulfur or phosphorus, it burns very easily. Many other chemicals can make dangerous mixtures with potassium chlorate.

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