An amphiprotic substance is a substance that can donate or accept a proton, H+
For a substance to be amphiprotic it must
Examples of amphiprotic species include, H2O, HCO3- , HSO4- , HPO42- and H2PO4-
Name of amphiprotic species | Chemical formula | Able to donate a proton, H+ | Able to accept a proton, H+ |
Water | H2O | H2O(l) → H+(aq) + OH-(aq) | H2O(l) + H+(aq) → H3O+(aq) |
Hydrogen carbonate ion | HCO3- | HCO3-(aq) → H+(aq) + CO32-(aq) | HCO3-(aq) + H+(aq) → H2CO3(aq) |
Hydrogen sulfate ion | HSO4- | HSO4-(aq) → H+(aq) + SO42-(aq) | HSO4-(aq) + H+(aq) → H2SO4(aq) |
Dihydrogen phosphate ion | H2PO4- | H2PO4-(aq) → H+(aq) + HPO42-(aq) | H2PO4-(aq) + H+(aq) → H3PO4(aq) |
Amphiprotic substances are a subset of amphoteric species since they can act as an acid or a base.