[Anhydrous Salt] * [Number of Water Molecules] H₂O

Where:

* [Anhydrous Salt] represents the chemical formula of the salt without any water molecules.

* [Number of Water Molecules] is a whole number representing the number of water molecules associated with each formula unit of the salt.

Example:

* CuSO₄ · 5H₂O is the formula for copper(II) sulfate pentahydrate. Here, the anhydrous salt is CuSO₄ and there are 5 water molecules associated with each formula unit.

Note:

* The dot (·) signifies that the water molecules are chemically bound to the salt, forming a hydrate.

* The number of water molecules in a hydrate is specific to the compound and is determined experimentally.

* Hydrates can be heated to drive off the water molecules, leaving behind the anhydrous salt.