amphoterisk

Amphoterisk is an adjective used to describe substances or species that can act as both acids and bases, depending on the chemical environment. The term is related to amphoteric, and in many languages it serves as a direct translation or variant; in English, amphoteric is the more common form. The root combines Greek amphoteros, meaning “having two ways,” with a suffix that forms an adjective.

In chemistry, an amphoterisk substance can behave as an acid by donating a proton or as a base by accepting one, and this dual behavior can also be described using Lewis acid–base concepts. The degree of amphotericity often depends on factors such as pH, temperature, and the presence of complementary reactants. Common examples include water (H2O), certain metal hydroxides like aluminum hydroxide Al(OH)3, zinc oxide ZnO, and various amino acids, which can exist as zwitterions under physiological conditions.

The concept is important for understanding acid-base equilibria in environmental chemistry, materials science, and biochemistry. Amphoteric oxides and hydroxides play roles in corrosion resistance, catalysis, and pollutant immobilization, while the amphotericity of amino acids underpins protein structure and function. Recognizing amphoterisk behavior helps predict solubility, precipitation, and buffering capacity in complex chemical systems.

See also: amphoteric, ampholyte, acid-base theory.