monohydration

Monohydration refers to the state of having a single molecule of water associated with a molecule of a substance, typically an ionic compound or a salt. This water molecule is incorporated into the crystal structure of the compound, forming a hydrate. The term "mono" signifies one, indicating that for each formula unit of the compound, there is exactly one water molecule. For example, copper(II) sulfate monohydrate has the chemical formula CuSO4·H2O. The presence of this water molecule can affect the physical properties of the compound, such as its solubility, melting point, and appearance.

In contrast to other hydrates like dihydrates or pentahydrates, monohydrates have the lowest ratio of water to solute among hydrated forms. The water molecule in a monohydrate is often referred to as "water of crystallization" or "lattice water" because it occupies specific positions within the crystal lattice of the substance. The formation and stability of monohydrates depend on factors like humidity, temperature, and atmospheric pressure. When heated, monohydrates can lose their water of crystallization, transforming into the anhydrous (water-free) form of the compound. This process is known as dehydration. Conversely, anhydrous compounds can sometimes absorb moisture from the air to form monohydrates or other hydrated species, a process called hydration. The study of hydrated compounds, including monohydrates, is important in various fields, including chemistry, materials science, and pharmaceuticals.