Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. The aim of this laboratory exercise is to present a high school hands-on laboratory experiment, focused on obtaining and investigating the properties of various polymorphic forms of aluminum oxide.
Amphoterism plays a key role when discussing the law of periodicity and periodic changes of acid—base properties of elements and their compounds. In many school syllabuses, that issue is based on third period elements, so the amphoteric substances are aluminum, aluminum oxide, and aluminum hydroxide.
Although demonstrating those properties for aluminum and aluminum hydroxide is relatively simple, the same reactions for alumina can be quite problematic. It is due to the fact that aluminum oxide exists in several polymorphic forms, and only one of them reacts with acids and bases. Moreover, the commercially available aluminum oxide materials are usually nonamphoteric. The exercise describes preparation of various polymorphic forms of aluminum oxide by thermal decomposition of aluminum hydroxide, and tests for its acid—base properties.
The experiment can be used as a separate activity, or as a part of a larger scenario considering the properties of third period oxides. It was successfully conducted with over high school K—11 students studying chemistry at standard and higher level according to the International Baccalaureate Diploma Programme.
Improve this question. Mithoron 4, 12 12 gold badges 36 36 silver badges 55 55 bronze badges. DevUt DevUt 6 6 bronze badges. I am afraid nobody knows yet. Yes one can predict from periodic trends like Mendeleev, but what is the fundamental cause? It is an open question I guess. Why is sodium oxide basic, why do nitrogen oxides react acidic, etc. You know, start with the simpler cases. Then look for reactions that show how Al oxide can do both.
Add a comment. Active Oldest Votes. This is indeed the case, as stated here for indium hydroxide since hydroxides are simply hydrated forms of their oxides, we can expect a similar nature for indium oxide as well : The result indicated conclusively that In OH 3 is only slightly amphoteric, being much more basic than acidic.
Before wrapping up the answer, I would like to re-iterate a point I made at the beginning of the answer: All these pathways are simply possible mechanisms, and there is no way of knowing whether they are completely correct or not without performing experiments. Improve this answer.
Yusuf Hasan Yusuf Hasan 2, 1 1 gold badge 14 14 silver badges 30 30 bronze badges. Yet in your explanations, you invoked a bridged structure for the ionic solid? From which source did you find aluminium oxide to exists as covalent molecules with a bridged structure?
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Email Required, but never shown. Featured on Meta. Now live: A fully responsive profile. Privacy Policy. Skip to main content. Acids and Bases. Search for:. Acid-Base Properties of Oxides Basic and Amphoteric Hydroxides Some metal hydroxides are amphoteric, or capable of acting as either an acid or base. Learning Objectives Identify the conditions under which amphoteric hydroxides act as acids.
Key Takeaways Key Points Amphoteric molecules can act as either acids or bases. Hydroxides with highly-charged metal cations are often amphoteric.
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