An amphiprotic substance is a substance that can donate or accept a proton, H+

For a substance to be amphiprotic it must

  1. contain a hydrogen atom which is able to be donated to another chemical species.
  2. be able to accept a hydrogen ion from another species.

Examples of amphiprotic species include, H2O, HCO3- , HSO4- , HPO42- and H2PO4-

An amphoteric substance is an oxide of an element that can act as both an acid or a base.

Common amphoteric substances are the oxides of the elements and beryllium, aluminum, zinc, tin and lead.


Aluminum oxide reacting with an acid:

Al2O3(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2O(l)

Aluminum oxide reacting with a base:

Al2O3(s) + 2NaOH(aq) + 3H2O(l) → 2Na[Al(OH)4](aq) or sodium tetrahydroxoaluminate


How to make Sherbet


Making sherbet is a great practical activity to show students the action of an acid on a carbonate.

When acids react with carbonates like bicarb of soda, carbon dioxide gas is produced.

General equation: Acid + metal carbonate → salt + water + carbon dioxide gas


Molar Mass

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