How to judge the acidity and alkalinity of amphoteric substances

If it is simple materials, the method to judge the acidity is to put the substance into an alkaline solution (generally, strong alkali, such as NaOH, is used to test the acidity of aluminum) and observe whether there are bubbles.

The method of judging alkalinity is the same, that is, put the substance in an acidic solution (such as HCl) and observe whether there are bubbles.

If it is an oxide, it is also placed in an acid-base solution to observe whether it is dissolved.