pentahydric

Pentahydric refers to a chemical compound that contains five molecules of water per molecule of the compound. This is also known as a pentahydrate. The water molecules are incorporated into the crystal structure of the compound, often through hydrogen bonding. When a pentahydrate is heated, it will lose its water molecules, a process called dehydration. The temperature at which this occurs depends on the specific compound. Many salts form hydrates, and the number of water molecules can vary widely. For example, copper(II) sulfate can exist as a pentahydrate, commonly known as blue vitriol, with the chemical formula CuSO4·5H2O. Sodium carbonate also forms a pentahydrate, Na2CO3·5H2O, which is sometimes referred to as thermonatrite. The presence of water molecules in the crystal lattice can affect the physical properties of the compound, such as its color, solubility, and melting point.