http___en.m.wikipedia.org_wiki_Potassium_chlorate.xml
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Калиев хлорат Калиевият хлорат е калиева сол на хлорната киселина със химическа формула KClO3. Друго наименование е "бертолетова сол" по името на Клод Бертоле, който е изследвал съединенията на хлора. Съединението има неутрален или слабо алкален характер и е силен окислител. При нагряване се разлага най-напред на калиев перхлорат и калиев хлорид: при по нататъшно нагряване калиевият перхлорат се разпада на калиев хлорид и кислород. Сумарното уравнение е: За разлика от напр. калиевия нитрат, калиевият хлорат може да отдаде всичкия кислород, който се съдържа в него. Освен това процеса на разлагане е екзотермичен (AH=-10,6 kcal/mol), поради тези причини бертолетовата сол надминава по окислителни свойства доста други съединения и смесите му с горими материали се запалват по-лесно. Като силно реактивоспособно съединение то не се среща в природата а се получава само по изкуствени методи. Най-често се получава при електролиза на воден разтвор на натриев хлорид[1]. Като междинен продукт се получава натриев хлорат, към който се добавя калиев хлорид за да се утаи калиевият хлорат. Може да се получи и чрез директна електролиза на разтвор на калиев хлорид. Неутралните и алкалните водни разтвори на бертолетовата сол не проявяват окислителни свойства. Кисели разтвори обаче действат като силни окислители заради отделянето на хлорна киселина. Съединението е слабо отровно, като леталната доза за възрастен е около 15 до 30 g. Главно приложение намира при получаването на хлорен диоксид, който от своя страна се използва за избелване. В някои държави се използва като евтин и ефективен хербицид. Калиевият хлорат е малко хигроскопичен и е предпочитан пред други хлорати като окислител в пиротехниката. Само по себе си съединението не е опасно, но смесите му със редуктори като сяра, метали (алуминий, магнезий,...), въглерод и горими органични материали може да проявят при обстоятелства експлозивен характер. Смесите със сяра могат да се самозапалят, като причина за това често се споменава образуването на малки количества сярна киселина на повърхността на серните частички. По тази причина се препоръчва замяната на калиевия хлорат във пиротехнически смеси с калиев перхлорат[2]. Сместа на бертолетовата сол с фосфор се нарича "смес на Армстронг" и може да се взриви и при най-леко триене или нагряване. Калиевият хлорат влиза в състава на барута за кибритените клечки. При триене на клечките в "стъргалото" хлоратът влиза в контакт с фосфора, който се съдържа там, и се запалва. Може да се използва за получаване на кислород в лабораторни условия, най-често в смес с манганов диоксид MnO2, който снижава температурата на разлагане на хлората. В автомобилната индустрия се прилага във въздушни възглавници. При удар на автомобила капсула, съдържаща калиев хлорат, отделя газове издуващи възглавницата.
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Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use. It is used - as an oxidizing agent, - to prepare oxygen, - as a disinfectant, - in safety matches, - in explosives (including IEDs[6]) and fireworks, - in cultivation, forcing the blossoming stage of the Longan tree, causing it to produce fruit in warmer climates.[7] ProductionEdit On the industrial scale, potassium chlorate is produced by passing chlorine into the hot milk of lime, subsequently adding the potassium chloride (Liebig process).[8] The electrolysis of KCl in aqueous solution is also used sometimes, in which the chloride ions formed at the anode react with KOH in situ. The low solubility of KClO3 in water causes the salt to conveniently isolate itself from the reaction mixture by simply precipitating out of solution. Potassium chlorate can be produced in small amounts by disproportionation in a sodium hypochlorite solution followed by metathesis reaction with potassium chloride:[9] - 3 NaClO → 2NaCl + NaClO3 - KCl + NaClO3 → NaCl + KClO3 It can also be produced by passing chlorine gas into a hot solution of caustic potash:[10] - 3 Cl2(g) + 6 KOH(aq) → KClO3(aq) + 5 KCl(aq) + 3 H2O(l) UsesEdit 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 stronger 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 rarely used in explosives now, as it is considered too sensitive for most uses. Another application of potassium chlorate is as the oxidizer in a smoke composition such as used in, e.g., smoke grenades. Since 2005, a cartridge with potassium chlorate mixed with lactose and rosin is used for generating the white smoke signalling the election of new pope by a papal conclave.[11] Potassium chlorate is often used in high school and college laboratories to generate oxygen gas.[citation needed] 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, 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: - 2 KClO3(s) → 3 O2(g) + 2 KCl(s) Heating it in the absence of a catalyst converts it into potassium perchlorate:[10] - 4 KClO3 → 3 KClO4 + KCl With further heating, potassium perchlorate decomposes to potassium chloride and oxygen: - KClO4 → KCl + 2 O2 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 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 can react with sulfuric acid to form a highly reactive solution of chloric acid and potassium sulfate: - 2 KClO3 + H2SO4 → 2 HClO3 + K2SO4 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 demonstration. SafetyEdit 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 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. See alsoEdit ReferencesEdit - ^ Seidell, Atherton; Linke, William F. (1952). [Google Books Solubilities of Inorganic and Organic Compounds]. Van Nostrand. - ^ a b c d e f g http://chemister.ru/Database/properties-en.php?dbid=1&id=331 - ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. - ^ a b c Potassium chlorate - ^ http://chem.sis.nlm.nih.gov/chemidplus/rn/3811-04-9 - ^ "Afghan bomb makers shifting to new explosives for IEDs". usatoday.com. - ^ Manochai, P.; Sruamsiri, P.; Wiriya-alongkorn, W.; Naphrom, D.; Hegele, M.; Bangerth, F. (February 12, 2005). "Year around off season flower induction in longan (Dimocarpus longan, Lour.) trees by KClO3 applications: potentials and problems". Scientia Horticulturae (Department of Horticulture, Maejo University, Chiang Mai, Thailand; Department of Horticulture, Chiang Mai University, Chiang Mai, Thailand; Institute of Special Crops and Crop Physiology, University of Hohenheim, 70593 Stuttgart, Germany) 104 (4): 379–390. Retrieved November 28, 2010. - ^ PeMи, Г. Kypc HeopraHичeckoй xиMиию, T. 1/ПepeBoд c HeMeцkoro пoд peд. A. B. HoBocëлoBoй. MockBa:Mиp, 1972.- c. 770//(translated from:) Heinrich Remy. Lehrbuch der anorganischen Chemie. XI Auflage. Band 1. Leipzig:Geest & Portig K.-G., 1960. - ^ http://chemistry.about.com/od/makechemicalsyourself/a/Potassium-Chlorate-From-Bleach-And-Salt-Substitute.htm - ^ a b Pradyot Patnaik. Handbook of Inorganic Chemicals. - ^ Daniel J. Wakin and Alan Cowell (March 13, 2013). "New Round of Voting Fails to Name a Pope". The New York Times. Retrieved March 13, 2013. - "Chlorate de potassium. Chlorate de sodium", Fiche toxicol. n° 217, Paris:Institut national de recherche et de sécurité, 2000. - Continuous process for the manufacture of potassium chlorate by coupling with a sodium chlorate production plant