Potassium chlorate is a compound containing
potassium
Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
,
chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
, with the molecular formula KClO
3. In its pure form, it is a white crystalline substance. After
sodium chlorate, it is the second most common
chlorate in industrial use. It is a strong
oxidizing agent
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
and its most important application is in safety
match
A match is a tool for starting a fire. Typically, matches are made of small wooden sticks or stiff paper. One end is coated with a material that can be ignited by friction generated by striking the match against a suitable surface. Wooden mat ...
es.
In other applications it is mostly obsolete and has been replaced by safer alternatives in recent decades. It has been used
* in
fireworks
Fireworks are a class of low explosive pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a large number of devices ...
,
propellants and
explosives
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
,
* to prepare
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
, both in the lab and in
chemical oxygen generator
A chemical oxygen generator is a device that releases oxygen via a chemical reaction. The oxygen source is usually an inorganic superoxide, chlorate, or perchlorate; ozonides are a promising group of oxygen sources. The generators are usually ig ...
s,
* as a
disinfectant
A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than s ...
, for example in medical
mouthwashes,
* in
agriculture
Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
as an
herbicide
Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...
.
Production
On the industrial scale, potassium chlorate is produced by the
salt metathesis reaction of
sodium chlorate and
potassium chloride:
: NaClO
3 + KCl → NaCl + KClO
3
The reaction is driven by the low solubility of potassium chlorate in water. The equilibrium of the reaction is shifted to the right hand side by the continuous precipitation of the product (
Le Chatelier's Principle
Le Chatelier's principle (pronounced or ), also called Chatelier's principle (or the Equilibrium Law), is a principle of chemistry used to predict the effect of a change in conditions on chemical equilibria. The principle is named after French ...
). The precursor sodium chlorate is produced industrially in very large quantities by
electrolysis
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...
of
sodium chloride
Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35. ...
, common table salt.
The direct electrolysis of
KCl in aqueous solution is also used sometimes, in which elemental chlorine formed at the
anode
An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...
reacts with KOH ''
in situ''. The low
solubility
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution.
The extent of the solubi ...
of KClO
3 in water causes the salt to conveniently isolate itself from the
reaction mixture
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...
by simply precipitating out of solution.
Potassium chlorate can be produced in small amounts by
disproportionation
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can ...
in a
sodium hypochlorite solution followed by
metathesis reaction with potassium chloride:
:3 NaOCl
(aq) → 2 NaCl
(s) + NaClO
3(aq)
:KCl
(aq) + NaClO
3(aq) → NaCl
(aq) + KClO
3(s)
It can also be produced by passing chlorine gas into a hot solution of caustic potash:
[Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, ]
:3 Cl
2(g) + 6 KOH
(aq) → KClO
3(aq) + 5 KCl
(aq) + 3 H
2O
(l)
Uses
Potassium chlorate was one key ingredient in early
firearms
A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions).
The first firearms originated in 10th-century China, when bamboo tubes ...
percussion caps (primers). It continues in that application, where not supplanted by
potassium perchlorate.
Chlorate-based
propellants are more efficient than traditional
gunpowder
Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). T ...
and are less susceptible to damage by water. However, they can be extremely unstable in the presence of
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...
or
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
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
Silver fulminate (AgCNO) is the highly explosive silver salt of fulminic acid.
Silver fulminate is a primary explosive, but has limited use as such due to its extreme sensitivity to impact, heat, pressure, and electricity. The compound becomes ...
, is used in trick
noise-makers known as "crackers", "snappers", "pop-its", or "bang-snaps", a popular type of novelty
firework.
Another application of potassium chlorate is as the oxidizer in a
smoke composition A smoke composition is a pyrotechnic composition designed primarily to generate smoke. Smoke compositions are used as obscurants or for generation of signaling smokes. Some are used as a payload of smoke bombs and smoke grenades.
Obscurants
Smok ...
such as that used in
smoke grenades. Since 2005, a cartridge with potassium chlorate mixed with
lactose
Lactose is a disaccharide sugar synthesized by galactose and glucose subunits and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from ' (gen. '), the Latin word for milk, plus the suffix ' ...
and
rosin is used for generating the white smoke signaling the election of new pope by a
papal conclave.
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 readily decomposes if heated while in contact with a
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
, typically
manganese(IV) dioxide (MnO
2). 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:
:
2 KClO3(s) -> DeltaMnO_2] 3 O2(g) + 2 KCl(s)
Heating it in the absence of a catalyst converts it into
potassium perchlorate:
:
4 KClO3 -> 3 KClO4 + KCl
With further heating, potassium perchlorate decomposes to
potassium chloride and oxygen:
:
KClO4 -> KCl + 2O2
The safe performance of this reaction requires very pure reagents and careful temperature control. Molten potassium chlorate is an extremely powerful oxidizer and spontaneously reacts with many common materials such as sugar. 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 generator
A chemical oxygen generator is a device that releases oxygen via a chemical reaction. The oxygen source is usually an inorganic superoxide, chlorate, or perchlorate; ozonides are a promising group of oxygen sources. The generators are usually ig ...
s (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
ValuJet Flight 592, plane crash. A fire on the space station
Mir was traced to oxygen generation candles that use a similar lithium perchlorate. The decomposition of potassium chlorate was also used to provide the oxygen supply for
limelights.
Potassium chlorate is used also as a
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and ...
. In Finland it was sold under trade name Fegabit.
Potassium chlorate can react with sulfuric acid to form a highly reactive solution of chloric acid and potassium sulfate:
:2 KClO
3 + H
2SO
4 → 2 HClO
3 + K
2SO
4
The solution so produced is sufficiently reactive that it spontaneously ignites if combustible material (sugar, paper, etc.) is present.
In schools, molten potassium chlorate is used in the dramatic
screaming jelly babies,
Gummy bear,
Haribo
Haribo ( ) is a German confectionery company founded by Hans Riegel Sr.. It began in Kessenich, Bonn, Germany. The name "Haribo" is a syllabic abbreviation formed from Hans Riegel Bonn. The company created the first gummy candy in 1960 in the ...
, and
Trolli
Trolli is a German manufacturer of confectionery. Its American arm was sold in 1996 and became a confectionery brand used by Ferrara Candy Company. Trolli sells gummy candies, marshmallows, and soft licorice gums in over 80 countries and has f ...
candy demonstration where the candy is dropped into the molten salt.
In chemical labs it is used to oxidize HCl and release small amounts of gaseous chlorine.
Insurgents in
Afghanistan
Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is borde ...
also use potassium chlorate extensively as a key component in the production of
improvised explosive devices. When significant effort was made to reduce the availability of
ammonium nitrate fertilizer in Afghanistan, IED makers started using potassium chlorate as a cheap and effective alternative. In 2013, 60% of IEDs in Afghanistan used potassium chlorate, making it the most common ingredient used in IEDs.
Potassium chlorate was also the main ingredient in the car bomb used in
2002 Bali bombings
The 2002 Bali bombings occurred on 12 October 2002 in the tourist district of Kuta on the Indonesian island of Bali. The attack killed 202 people (including 88 Australians, 38 Indonesians, 23 Britons, and people of more than 20 other national ...
that killed 202 people.
Potassium chlorate is used to force the blossoming stage of the
longan
''Dimocarpus longan'', commonly known as the longan () and dragon's eye, is a tropical tree species that produces edible fruit. It is one of the better-known tropical members of the soapberry family Sapindaceae, to which the lychee and rambu ...
tree, causing it to produce fruit in warmer climates.
Safety
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 burns vigorously in combination with virtually any combustible material, even those normally only slightly flammable (including ordinary dust and lint). Mixtures of potassium chlorate and a fuel can ignite by contact with sulfuric acid, so it should be kept away from this reagent.
Sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...
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
Antimony trisulfide (Sb2S3) is found in nature as the crystalline mineral stibnite and the amorphous red mineral (actually a mineraloid) metastibnite. It is manufactured for use in safety matches, military ammunition, explosives and fireworks. I ...
) are very dangerous to prepare, as they are extremely shock sensitive.
See also
*
Chloric acid
References
*"Chlorate de potassium. Chlorate de sodium", ''Fiche toxicol. n° 217'', Paris:Institut national de recherche et de sécurité, 2000. 4pp.
Continuous process for the manufacture of potassium chlorate by coupling with a sodium chlorate production plant
External links
{{Chlorates
Potassium compounds
Chlorates
Pyrotechnic oxidizers