高锰酸钾的制备

高锰酸钾的制备 一、实验目的 1(了解由软锰矿制取高锰酸钾的原理和方法。 2(了解锰的各种氧化态化合物之间相互转化的条件。 3(练习由启普发生器制取二氧化碳的技术。 4(练习加热、浸取、过滤、蒸发、浓缩、结晶等操作。 二、实验原理 3MnO+6KOH+KClO=3KMnO+KCl+3HO 23242 将软锰矿(主要成分为MnO)和KClO在碱性介质中强热可制得23 墨绿色KMnO熔体。 24 2-当降低溶液的pH值时，MnO即发生歧化反应(只有在强4 碱性pH,14.4溶液中才是稳定的)，得到紫红色KMnO溶4液。例如:在溶液中通人CO气体: 2 3KMnO+2CO?2KMnO+ MnO+2KCO 2424223 滤去MnO固态，溶液蒸发浓缩，就会析出KMnO晶体。 24 三、实验内容 称取7gKOH(s)和5gKClO(s)放入铁坩埚中，混合均匀，3 用铁夹将铁坩埚夹紧，固定在铁架上，小火加热，并用洁净的铁丝搅拌混合(或一手用坩埚钳夹住铁坩埚，一手用铁棒搅拌)。待混合物熔融后，边搅拌，边逐渐加入5gMnO(s)，即可观察到熔2 融物黏度逐渐增大，再不断用力搅拌，以防结块。如反应剧烈使熔融物溢出时，可将铁坩埚移离火焰。在反应快要干涸时，应不断搅development is limited by the handling capacity of the airport, not in-situ expansion. Jinsha River and minjiang rivers, the Yangtze River traverses northern border in Yibin city, with good conditions for development of water transport, but water with speed ... Rate of 10.9% per cent. In recent years, Yibin city, stepping up construction of transport infrastructure at the same time, increase the intensity of high-grade highway construction, and the overall technical levels improved significantly, which succeeds in improving road 拌，使呈颗粒状，以不结成大块粘在坩埚壁上为宜。待反应物干涸后，加大火焰，在仍保持翻动下强热4,8min，即得墨绿色的锰酸钾。 2(浸取 待物料冷却后，取出反应物，在研钵中研细。在烧杯中用40mL蒸馏水浸取，搅拌、加热使其溶解，静置片刻，倾出上三层清液与另一个烧杯中。依次用20mL蒸馏水、20mL 4%KOH溶液重复浸取。合并三次浸取液(连同熔物渣)，便得墨绿色的锰酸钾溶液。 3(锰酸钾的歧化 在浸取液中通人CO气体，使KMnO歧化为KMnO和2244MnO，用pH试纸测试溶液的pH值，当溶液的pH值达到10,2 11之间时，即停止通CO。然后把溶液加热，趁热用砂芯漏斗2 抽滤，滤去MnO残渣。 2 4(结晶 把滤液移至蒸发皿内，用小火加热，当浓缩至液面出现微小晶体时，停止加热，冷却，即有KMnO晶体析出。最后用砂芯4 漏斗抽滤，把KMnO晶体尽可能抽干，称量。计算产率。记录4 晶体的颜色和形状。 四、实验指导与 1(CO通得过多，溶液的pH值会太低，则溶液中生成大量2 KHCO: 3 development is limited by the handling capacity of the airport, not in-situ expansion. Jinsha River and minjiang rivers, the Yangtze River traverses northern border in Yibin city, with good conditions for development of water transport, but water with speed ... Rate of 10.9% per cent. In recent years, Yibin city, stepping up construction of transport infrastructure at the same time, increase the intensity of high-grade highway construction, and the overall technical levels improved significantly, which succeeds in improving road CO+2KOH?KCO+HO 2232 KCO+CO+HO?2KHCO 23223 由于KHCO的溶解度比KCO小得多，在溶液浓缩时，KHCO3233就会和KMnO一起析出。 4 2(由于KMnO溶液紫色的干扰，溶液pH值可近似测试如下:4 用洁净玻璃棒蘸取溶液滴到pH试纸上，随着试纸上液体的层析，试纸上红棕色的边缘所显示的颜色，即反映溶液的pH值。 development is limited by the handling capacity of the airport, not in-situ expansion. Jinsha River and minjiang rivers, the Yangtze River traverses northern border in Yibin city, with good conditions for development of water transport, but water with speed ... Rate of 10.9% per cent. In recent years, Yibin city, stepping up construction of transport infrastructure at the same time, increase the intensity of high-grade highway construction, and the overall technical levels improved significantly, which succeeds in improving road