What is potassium chlorate?
Potassium salt of chloric acid (one of the four oxygen-containing acids formed by chlorine: hypochlorous - HClO, chloride - HClO2, chloric - HClO3 and chloric - HClO4) is called potassium chlorate, its formula is KClO3. In appearance, this salt is crystals (colorless), which are slightly soluble in water (at 20 º, only 7.3 g of salt dissolves in 100 cm3 of water), but with increasing temperature the solubility increases. Its other famous name is Bertolet's salt. The molecular mass of the substance is 122.55 atomic mass units, the density is 2.32 g / cm3. Salt melts at 356 º, decomposes at about 400 º.
Discovery of Berthollet Salt
For the first time (in 1786) potassium chlorate was obtained by the French chemist Claude Bertollet. He passed chlorine through a concentrated hot potassium hydroxide solution. The equation of the reaction by which the salt was obtained is as follows: 3Cl2 + 6KOH → 5KCl + KClO3 + 3H2O. As a result of this reaction, potassium chlorate precipitates as a white precipitate. Since it is slightly soluble in cold water, it is easily separated from other salts by cooling the solution. Since its discovery, Bertolet salt has been the most common and useful product of all chlorates. Currently, KClO3 is commercially available.
Chemical properties
Bertoletova salt is a strong oxidizing agent. When it interacts with concentrated hydrochloric acid (HCl), free chlorine is released. This process is described by the equation of the chemical reaction: 6HCl + KClO3 → 3Cl ↑ + KCl + 3 H2O. Like all chlorates, this substance is highly toxic. In molten form, KClO3 vigorously supports combustion. In a mixture with easily oxidized substances (reducing agents), such as sulfur, phosphorus, sugar and other organic substances, potassium chlorate explodes from shock or friction. Sensitivity to these effects is enhanced in the presence of ammonium salts and bromates. Upon careful (heating to 60 º) oxidation of potassium chlorate with oxalic acid, chlorine dioxide is obtained, the process proceeds according to the reaction equation: 2KClO3 + H2C2O4 → K2CO3 + CO2 + H2O + 2ClO2. Chlorine oxide is used in the bleaching and sterilization of various materials (paper pulp, flour, etc.), and can also be used for de-phenolization of wastewater from chemical plants.
The use of potassium chlorate
Of all the chlorates, Bertolet's salt is most widely used. It is used in the manufacture of dyes, matches (make the match head combustible, the raw material is moistened potassium chlorate according to TU 6-18-24-84), fireworks, disinfectants, and chlorine dioxide. Due to the high danger of compounds with potassium chlorate, they are practically not used in the manufacture of explosives for industrial and military purposes. Very rarely, potassium chlorate is used as an initiating explosive. Sometimes used in pyrotechnics, as a result, color-flame compositions are obtained. Salt used to be used in medicine: weak solutions of this substance (KClO3) were used for some time as an antiseptic for external gargling. Salt at the beginning of the 20th century was used to produce oxygen under laboratory conditions, but because of the danger of experiments, they were discontinued.
Getting potassium chlorate
One of the following methods: by chlorination of potassium hydroxide, as a result of the exchange reaction of chlorates with other salts, by electrochemical oxidation in aqueous solutions of metal chlorides, a Bertolet salt can be obtained. Obtaining it on an industrial scale is often carried out by the disproportionation reaction of hypochlorites (hypochlorous acid salts). Technologically, the process is drawn up in different ways. More often it is based on the reaction between calcium chlorate and potassium chloride: Ca (ClO3) 2 + 2KCl → 2KClO3 + CaCl2. Then, the formed Bertolet salt from the mother liquor is isolated by crystallization. Potassium chlorate is also obtained by the modified Bertollet method in the electrolysis of potassium chloride: chlorine formed during electrolysis interacts with potassium hydroxide, the resulting potassium hypochlorite KClO then disproportionates KClO3 chlorate and potassium chloride KCl to potassium.
Potassium Chlorate Decomposition
At a temperature of about 400 º, decomposition of bertoletova salt occurs. As a result, oxygen and potassium perchlorate are released: 4KClO3 → KCl + 3KClO4. The next stage of decomposition proceeds at temperatures from 550 to 620 º: KClO4 → 2O2 ↑ + KCl. On catalysts (they can be copper oxide CuO, iron oxide (III) Fe2O3 or manganese oxide (IV) MnO2) decomposition proceeds at a lower temperature (from 150 to 300 º) and in one stage: 2KClO3 → 2KCl + 3O2.
Security measures
Bertoletova salt is an unstable explosive chemical that can explode when mixed, stored (for example, next to reducing agents on the same shelf in the laboratory or in the same warehouse), grinding or other operations. The explosion could result in injury or even death. Therefore, when receiving, using, storing or transporting potassium chlorate, the requirements of Federal Law 116. The facilities where these processes are organized belong to hazardous production facilities.