======Amphoteric Aluminium======


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====Summary====                   
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====Procedure====  
  - Start with aluminum hydroxide (Al(OH)₃).  
  - Heat it gently in a furnace (about 250 °C for 30 minutes) or over a Bunsen burner (450 °C for a few minutes) to form Al₂O₃.
  - Place a small amount of the oxide into dilute hydrochloric acid (with methyl orange) and note if it reacts.
  - Place another small amount into dilute sodium hydroxide (with phenolphthalein) and note if it reacts.

====Links==== 
Amphoteric Hydroxides - Chemistry and Biochemistry Demo lab at OSU: 
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📄 Obtaining and Investigating Amphoteric Properties of Aluminum
Oxide in a Hands-On Laboratory Experiment for High School
Students - Journal of Chemical Education: [[https://pendidikankimia.walisongo.ac.id/wp-content/uploads/2018/10/22-26.pdf]]\\


====Variations====
  * Try similar acid–base tests on other oxides from the same period (e.g., Na₂O, MgO, SiO₂).  




====Safety Precautions====
  * Handle hot crucibles or dishes with tongs and allow them to cool before touching.  
  * Avoid breathing in powders; keep the area well ventilated.  
  * Use only dilute acids and bases for testing, but rinse any spills with water.




====Questions to Consider====
  * What does it mean for a substance to be amphoteric? (It reacts with both acids and bases.)   
  * What changes happen when aluminum hydroxide is heated? (It loses water and becomes Al₂O₃.)  
  * How does this experiment connect to the periodic table trend for oxides across Period 3? (Oxides change from basic to amphoteric to acidic across the period.)