Preparation of Aluminium Hydroxide with Mechanochemical Synthesis in the Middle School Laboratory Lesson

Mechanochemical reactions proceed if solid reactants combine together by grinding, milling or kneading with no or minimal solvent. It is possible to observe changes: fizzing, foaming, colour changes, water release. This process is manually simple and there are several mechanochemical reactions which can be demonstrated during school laboratory lessons. For high school pupils there exist five possibilities of inorganic synthesis: mechanochemical synthesis, crystallisation, precipitation, filtration and decantation. The preparation of aluminium hydroxide in the school laboratory is described in this paper. Five mechanochemical reaction schemes were tested by pupils in their laboratories. The pupils conducted the experiments and filled in worksheets to accompany the practical. On the basis of their results, a suitable procedure for school use is suggested.