Monohydraattiset

Monohydraattiset refers to a chemical compound that contains one molecule of water per molecule of the compound within its crystal structure. This water molecule is known as a water of crystallization or hydration. When a substance forms a hydrate, it incorporates water molecules into its regular lattice structure during the crystallization process. The presence of this water molecule can significantly influence the physical properties of the compound, such as its melting point, solubility, and density, compared to its anhydrous (water-free) form.

The term "monohydrate" is commonly used to describe such compounds. For example, sodium sulfate monohydrate (Na2SO4·H2O) is a stable crystalline form of sodium sulfate that includes one water molecule per formula unit. This is distinct from other hydrated forms, such as sodium sulfate decahydrate (Na2SO4·10H2O), which contains ten water molecules. The number of water molecules in the hydrate is indicated by a prefix: mono- for one, di- for two, tri- for three, and so on, up to deca- for ten. Beyond ten, prefixes like hepta-, dodeca-, or poly- might be used.

The water molecules in a monohydrate are typically held in the crystal lattice by relatively weak bonds, such as hydrogen bonds or electrostatic interactions with the ions of the compound. Under certain conditions, such as heating or exposure to a drier atmosphere, the water of hydration can be lost, leading to the formation of the anhydrous compound. This process is known as dehydration. Conversely, anhydrous compounds can absorb moisture from the air to form hydrates, a process called hydration or hygroscopy. The study of hydrates, including monohydrates, is important in various fields, including chemistry, pharmaceuticals, and materials science.