Amphoteric

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 kations, such as zinc from manganese.

See also amphiprotic. Or ampholytic