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Amphoteric describes something made of two components, or acting like two different components.

In chemistry, it means a substance that can act as either acid or base. An example is amino acids and water. Similar many metals, such as zinc, tin, aluminium or beryllium. E.g. Zinc-oxide ZnO reacts differently depending on the pH of the solution:

In acids:
ZnO + 2H+ --> Zn2+ + H2O
In bases:
ZnO + H2O + 2OH- --> [Zn(OH)4]2-

This effect can be used to separate different cations, such as zinc from manganese.

See also amphiprotic. Or ampholytic\n