基于绿色化学理念的微型实验设计--以氯水制备为例

通过医用注射器和输液器对氯水制备实验进行微型化和密闭化设计,实验现象非常明显,便于课堂演示操作,又可较长时间地保存药剂。改进实验在氯水的制取、保存和取用过程中都较好地避免了氯气外逸,实现了“零污染”。对教材实验进行微型、密闭设计,不仅保障了师生的身体健康,又可以减少实验前的准备工作,节约实验时间。因此鼓励师生对教材中的实验进行大胆设计,细心操作,以提高师生对微型实验的设计能力,激发学生的学习兴趣,促进绿色化学教育的可持续发展。

Preparation and characteristic research of anhydrous magnesium chloride with dehydrated ammonium carnallite

Taking the saline lake bischofite and NH4Cl that was removed with the ammonia method and continuously followed by filtration as raw materials with a molar ratio of 1∶1 of MgCl2 to NH4Cl, ammonium carnallite was synthesized. And then the ammonium carnallite was dehydrated to some extent at 160℃ for 4 h. Ammonium carnallite reacted with ammonia at 240℃ for 150 min and the ammonation ammonium carnallite was produced. Finally, the ammonation ammonium carnallite was calcined at 750℃ into anhydrous magnesium chloride containing only 0.1%（mass fraction） of MgO. On the other hand, dehydrated ammonium carnallite was mixed with the solid ammonium chloride at mass ratio 1∶4 at high temperature and with the differential pressure of NH3 above 30.5kPa. The dehydrated ammonium carnallite of mixture was dehydrated at 410℃, and then calcined at 700℃ into anhydrous magnesium chloride with only 0.087%（mass fraction） of MgO. X-ray diffraction and electron microscopy analysis results prove that anhydrous magnesium chloride obtained by both methods hasn’t mixed phases, the particle is large and even has good dispersion, which is suitable for preparation of metal magnesium in the electrolysis.

中学化学实验改进二三则

中学教材中有的实验操作方法在实际应用中存在不足。笔者对三个实验进行了创新改进，改进之后的方法具有操作简单、实验现象更明显等优点，在吸引学生注意力，培养学生兴趣，锻炼学生的实验操作技能等方面起到了更好的作用。