Chemistry – Acids, bases and salts - Preparation of salts | e-Consult

Hydrated substance: A hydrated substance is a chemical compound that has water molecules chemically bound within its crystal structure. These water molecules are typically held in a specific ratio to the compound. The water molecules are not simply present as free water; they are an integral part of the compound's structure.

Anhydrous substance: An anhydrous substance is a chemical compound that contains no water molecules chemically bound within its structure. It is a pure substance devoid of water.

Difference: The key difference lies in the presence or absence of chemically bound water. Hydrated substances *contain* water as part of their chemical formula and structure, while anhydrous substances *do not*.