hydraatteina

Hydraatteina is a term used to describe a substance that has incorporated water molecules into its crystal structure. These incorporated water molecules are known as water of crystallization or hydration water. When a compound exists in its hydrated form, it is referred to as a hydrate. The number of water molecules associated with each formula unit of the compound is indicated by a coefficient preceding the water molecule in the chemical formula. For example, copper(II) sulfate pentahydrate has the formula CuSO4·5H2O, meaning that for every one formula unit of copper(II) sulfate, there are five molecules of water incorporated into its structure.

The presence of water of crystallization can significantly affect the physical properties of a compound, such as its color, solubility, and melting point. For instance, anhydrous copper(II) sulfate is a white powder, while copper(II) sulfate pentahydrate is a bright blue crystalline solid. Heating a hydrate often leads to the removal of its water of crystallization, a process called dehydration, resulting in the formation of the anhydrous compound. Some hydrated compounds can readily absorb moisture from the atmosphere, a property known as hygroscopy. Conversely, other hydrates may lose their water of crystallization spontaneously when exposed to dry air, a phenomenon called efflorescence. The formation of hydrates is a common occurrence in the solid state for many ionic compounds and some molecular compounds.