Why is common salt called hydrated salts?

Common salt, or sodium chloride (NaCl), is not considered a hydrated salt. Hydrated salts are salts that contain water molecules bonded to their ionic structure.

Common salt, in its pure form, does not contain any water molecules. It is an ionic compound composed of positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-) held together by strong electrostatic forces.

Hydrated salts, on the other hand, have a specific number of water molecules associated with their ionic structure. These water molecules are chemically bonded to the ions, forming a crystalline structure. Some examples of hydrated salts include copper sulfate pentahydrate (CuSO4·5H2O), which contains five water molecules per copper sulfate unit, and sodium carbonate decahydrate (Na2CO3·10H2O), which contains ten water molecules per sodium carbonate unit.

In summary, common salt is not a hydrated salt because it does not contain any water molecules as part of its chemical structure.