Potassium chlorate

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Potassium chlorate

General
Other names	Potassium chlorate(V), Potcrate
Molecular formula	KClO₃
Molar mass	122.55 g/mol
Appearance	White crystals or powder
CAS number	[3811-04-9]
Properties
Density and phase	2.32 g/cm³, solid
Solubility in water	7.3 g/100 ml (20 °C) (70F)
Solubility variation	Varies greatly on temperature
Melting point	356 °C
Boiling point	~400 °C decomp.
Structure
Coordination geometry	?
Crystal structure	?
Hazards
MSDS	External MSDS
EU classification	Oxidant (O) Harmful (Xn) Dangerous for the environment (N)
NFPA 704	0 2 3 OX
R-phrases	R9, R22, R51/53
S-phrases	S2, S13, S17, S46, S61
Flash point	none
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	Potassium bromate Potassium iodate
Other cations	Ammonium chlorate Sodium chlorate
Related compounds	Potassium chloride Potassium hypochlorite Potassium chlorite Potassium perchlorate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Potassium chlorate is a compound containing potassium, chlorine and oxygen, with the chemical formula K[ClO₃]. 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:

As an oxidizing agent.
To prepare oxygen.
As a disinfectant, especially in bleach.
In safety matches.
In explosives and fireworks.

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 is used in some formulas of gunpowder, generally replacing the less powerful ingredient potassium nitrate. Although chlorate-based propellants are more efficient than traditional gunpowder and are less susceptible to damage by water, they can be extremely unstable due to the sulfur present and are much more expensive. Chlorate propellants must only be used in equipment designed for them; failure to follow this precaution is a common source of accidents.

When mixed with other materials, it may form a high 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 often used in highschool 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) oxide (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) → 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 the oxygen-supply systems of aircraft, 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 is sold under trade name Fegabit.