Potassium Permanganate - Potassium Permanganate

KMnO ₄ (158.03). It is obtained by heating pyrolusite MnO ₂ with KOH to give potassium manganate K ₂ MnO _{4 , which is then extracted with water and electrolytically oxidized. Orthorhombic ionic crystal. Deep reddish purple crystals (green in reflected light) according to charge transfer spectroscopy. MnO 4 -ions} are tetrahedral. Mn ^- O approx. 1.63 Å. ∠O-Mn-O approx. 110°. Density 2.70 g cm ^-3 . When heated above 200 °C, it decomposes (first to K ₂ MnO ₄ , MnO ₂ , O ₂ , and then to Mn ₂ O ₃ ). It is quite stable at room temperature in air, but decomposition is accelerated by sunlight. Soluble in water (6.51 g/100 g (20 °C)). It decomposes slowly even in aqueous solution. When the aqueous solution is made strongly alkaline, it generates oxygen and turns into green K ₂ MnO _4. In acidic conditions, K ₂ MnO ₄ disproportionates, partially becoming KMnO ₄ and turning purple. This is a common property of permanganic acid (salts), and the aqueous solution of a representative K salt is also called chameleon solution. It is a strong oxidizing agent that oxidizes various substances. In particular, in acidic sulfuric acid, it quantitatively oxidizes reducing agents and is reduced, disappearing the deep purple color, making it useful for redox titrations (see other terms: permanganate titration). In addition to being used as a titration reagent, it is also used as an oxidizing agent in many manufacturing processes for saccharin, ascorbic acid, and other organic compounds. It is also used to disinfect drinking water, and as a bleaching agent for wax, oils, and straw. [CAS 7722-64-7]

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

KMnO₄(158.03)．軟マンガン鉱MnO₂をKOHと加熱処理して得たマンガン酸カリウムK₂MnO₄を，水で抽出後電解酸化すると得られる．斜方晶系のイオン結晶．電荷移動スペクトルによる濃い赤紫色の結晶(反射光では緑色)．MnO₄^－イオンは四面体型．Mn-O約1.63 Å．∠O-Mn-O約110°．密度2.70 g cm^－3．加熱すると200 ℃ 以上で分解する(まずK₂MnO₄，MnO₂，O₂ になり，さらにMn₂O₃となる)．室温，空気中ではかなり安定であるが，太陽光で分解が促進される．水に可溶(6.51 g/100 g(20 ℃))．水溶液中でも徐々に分解する．水溶液は強アルカリ性にすると，酸素を発生して緑色のK₂MnO₄にかわる．K₂MnO₄は，酸性では不均化して一部KMnO₄となり紫色となる．これは過マンガン酸(塩)共通の性質であるが，そのうちの代表的なK塩の水溶液をカメレオン液ともいう．強力な酸化剤で，種々の物質を酸化する．とくに硫酸酸性では，還元剤を定量的に酸化し，自身は還元されて濃紫色が消失することを利用して，酸化還元滴定に利用される([別用語参照]過マンガン酸塩滴定)．滴定試薬のほかに，酸化剤として，有機合成でサッカリン，アスコルビン酸など多くの製造過程で利用される．また，飲料水の殺菌，さらにワックス，油脂，麦ワラなどの漂白剤に用いられる．[CAS 7722-64-7]

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