dihüdraat

Dihüdraat, or dihydrate, is a chemical compound that contains two water molecules per formula unit in its crystalline form. In hydrates, these water molecules are incorporated into the crystal lattice or bound to cations as coordinated water, influencing properties such as solubility, stability, and color. Two water molecules per formula unit distinguish dihydrates from monohydrates (one water) and higher hydrates (three or more). The water can be lattice water (waters of crystallization) or coordinated water bound to a metal center, depending on the compound.

Dihüdraati can form when salts crystallize from aqueous solutions under conditions that favor hydration. The dihydrate form may dehydrate upon heating, yielding the anhydrous salt or a lower hydrate; rehydration can occur upon exposure to moisture. The dehydration and rehydration behaviors are important for applications, storage, and handling.

Common examples include calcium sulfate dihydrate (gypsum, CaSO4·2H2O), a widely used mineral in construction and art, and magnesium sulfate dihydrate (Epsom salt, MgSO4·2H2O), used in medicine, agriculture, and bath applications. Other dihydrates occur among organic and inorganic salts, as well as certain metal complexes that crystallize with two water molecules per formula unit.

Dihüdraat forms are a key aspect of the broader study of hydrates, illustrating how water incorporation alters physical properties and phase behavior of compounds.