hemihidrát

Hemiydrát is a chemical term referring to a hydrate that contains one molecule of water for every two formula units of the compound. This means the stoichiometric ratio of water to the anhydrous compound is 1:2. The prefix "hemi-" signifies half, and in this context, it refers to half a mole of water per mole of the substance.

Hemiydrates are a common form of crystalline hydrates. The water molecules are incorporated into the crystal lattice of the compound in a specific, ordered manner. The properties of a hemiydrate can differ significantly from its anhydrous form and other hydrated forms, including melting point, solubility, and stability. For example, the hemiydrate of calcium sulfate, known as plaster of Paris, has distinct properties that make it useful in construction and art.

The formation of hemiydrates is typically a result of crystallization from aqueous solutions under specific temperature and concentration conditions. The exact structure and stability of hemiydrates depend on the chemical nature of the compound and the forces holding the water molecules within the crystal lattice. When heated, hemiydrates can lose their water of hydration, often transforming into the anhydrous form or other hydrates.