Avhydrert

Avhydrert is a Norwegian adjective used to describe a substance from which water of hydration has been removed, resulting in a state with little or no bound water. It is used mainly in chemistry, mineralogy, and materials science to distinguish from hydrert (hydrated) and from simply tørket (dried). The key concept is water of hydration—the water molecules chemically bound within a crystal lattice—that is eliminated during dehydration. The term is formed from av- (away) and hydrert (hydrated), with roots in Greek hydor meaning water.

In practice, avhydrerte forms occur when hydrated compounds are heated or subjected to reduced pressure, removing their water of crystallization. A classic example is copper sulfate pentahydrate (CuSO4·5H2O), which loses its water upon heating to become an avhydrert, anhydrous CuSO4. In geology and materials science, dehydration reactions produce avhydrerte minerals and compounds. The opposite process is rehydrering (rehydration), where water is reintroduced to a substance.

In everyday Norwegian, avhydrert is a relatively technical term; more common words for drying processes are tørket or avtørket, depending on nuance. Avhydrert specifically emphasizes the chemical removal of bound water rather than generic moisture loss.

See also: rehydrering, dehydration, anhydrous.