Definition - What does Amphoteric mean?
Amphoteric refers to an ion molecule or chemical entity that can act as an acid, or in some cases, a base. The term is derived from "amphoteroi," a Greek word which means "both." Some examples of metals that are amphoteric include:
The degree of amphoterism depends on the state of oxidation of the ion molecule present in the metal.
Corrosionpedia explains Amphoteric
Amphoteric molecules either act as a base or an acid depending on the central ion's electropositivity. For instance, hydroxides are a perfect example of amphoterics as they could act as both. However, it must be noted that there are hydroxides that are basic only.
If a hydroxide is considered amphoteric, it means that the central ion has adequate electropositivity to draw the density of the electron off the oxygen of the atom, which in turn destabilizes the hydrogen ion.
In the industries, amphoteric surfactants are used to inhibit corrosion in mild steel that is subjected to varying pH and atmospheric conditions. The existence of the amphoteric surfactants within the aqueous solution affects both the anodic and cathodic areas of polarization.
Amphoteric surfactants have a great ability to protect metal surfaces, making them one of the best tools to inhibit corrosion in steel and other materials used in various industries.