氢氧化钾的制备与特殊应用
Preparation and special application of potassium hydroxide
制备
Preparation
历史上,氢氧化钾是通过向氢氧化钙(熟石灰)的浓溶液中加入碳酸钾来制备的。盐复分解反应导致固体碳酸钙沉淀,留下氢氧化钾在溶液中:Ca(OH)2+K2CO3→CaCO3+2KOH。
Historically, potassium hydroxide was prepared by adding potassium carbonate to a concentrated solution of calcium hydroxide (hydrated lime). The salt double decomposition reaction leads to the precipitation of solid calcium carbonate, leaving potassium hydroxide in the solution: Ca (OH) 2+k2co3 → caco3+2koh.
过滤掉沉淀的碳酸钙并将溶液煮沸,得到氢氧化钾(“煅烧或苛性钾”)。这种生产氢氧化钾的方法一直占主导地位,直到19世纪后期,它才被目前一直使用的电解氯化钾溶液的方法所取代。该方法类似于氢氧化钠的制造(见氯碱工艺):2KCl+2H2O→2KOH+Cl2+H2。
Filter the precipitated calcium carbonate and boil the solution to give potassium hydroxide ("calcined or caustic potassium"). This method of producing potassium hydroxide was dominant until the late 19th century, when it was replaced by the method of electrolyzing potassium chloride solution. This method is similar to the manufacturing of sodium hydroxide (see chlor alkali process): 2kcl+2h2o → 2koh+cl2+h2.
市售的氢氧化钾通常是半透明颗粒状,由于氢氧化钾具有吸湿性,所以在空气中会发黏。因此,氢氧化钾通常含有不同量的水(和碳酸盐一样)。它在水中的溶解是强放热的。浓缩的水溶液有时被称为钾溶液。即使在高温下,固体氢氧化钾也不容易脱水。
The commercially available potassium hydroxide is usually translucent and granular. Due to its hygroscopicity, it will become sticky in the air. Therefore, potassium hydroxide usually contains different amounts of water (like carbonate). Its dissolution in water is strongly exothermic. Concentrated aqueous solutions are sometimes called potassium solutions. Even at high temperature, solid potassium hydroxide is not easy to dehydrate.
在较高温度下,固体氢氧化钾在氯化钠晶体结构中结晶。OH基团要么是快速无序的,要么是随机无序的,因此OH基团实际上是半径为1.53的球形阴离子(大小在Cl和F之间)。在室温下,?OH基团有序的,K中心周围的环境是无序的,根据OH基团的取向,K-OH距离范围为2.69至3.15?。氢氧化钾形成一系列结晶水合物,即一水氢氧化钾KOHH2O,二水氢氧化钾KOH2H2O和四水氢氧化钾KOH4H2O。
At higher temperature, solid potassium hydroxide crystallizes in the crystal structure of sodium chloride. OH groups are either rapidly disordered or randomly disordered, so oh groups are actually spherical anions with a radius of 1.53 (between Cl and F). At room temperature,? The OH groups are ordered, and the environment around the k center is disordered. According to the orientation of OH groups, the k-oh distance ranges from 2.69 to 3.15?. Potassium hydroxide forms a series of crystalline hydrates, namely potassium hydroxide monohydrate kohh2o, potassium hydroxide dihydrate koh2h2o and potassium hydroxide tetrahydrate koh4h2o.
像氢氧化钠一样,氢氧化钾表现出很高的热稳定性。气体状态下是二聚体。由于其高稳定性和相对低的熔点,它通常被熔融铸造成小球或棒,具有低表面积和易携带的性质。
Like sodium hydroxide, potassium hydroxide exhibits high thermal stability. It is dimer in gas state. Because of its high stability and relatively low melting point, it is usually melt cast into small balls or rods with low surface area and easy to carry.
特殊应用
Special applications
像氢氧化钠一样,氢氧化钾吸引了许多特殊的应用,几乎所有的应用都依赖于它作为一种强化学碱的性质,以及随之而来的降解许多材料的能力。例如,在通常被称为“化学火化”或“再分解”的过程中,氢氧化钾加速动物和人类软组织的分解,只留下骨头和其他硬组织。昆虫学家希望研究昆虫解剖的精细结构,可以使用10%氢氧化钾水溶液来应用这一过程。
Like sodium hydroxide, potassium hydroxide has attracted many special applications, almost all of which depend on its properties as a strengthening alkali and its subsequent ability to degrade many materials. For example, in a process commonly referred to as "chemical cremation" or "re decomposition", potassium hydroxide accelerates the decomposition of soft tissues in animals and humans, leaving only bones and other hard tissues. Entomologists hope to study the fine structure of insect anatomy, and can use 10% potassium hydroxide aqueous solution to apply this process.
在化学合成中,氢氧化钾和氢氧化钠的选择取决于所得盐的溶解度或质量。氢氧化钾的腐蚀性使其成为清洁和消毒表面的试剂和制剂中的一种有用成分,并且其本身可以抵抗氢氧化钾的腐蚀。
In chemical synthesis, the choice of potassium hydroxide and sodium hydroxide depends on the solubility or quality of the salt. The corrosivity of potassium hydroxide makes it a useful ingredient in reagents and preparations for cleaning and disinfecting surfaces, and it itself can resist the corrosion of potassium hydroxide.
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