4.3 Hydrates

A hydrate is a compound that has a specific number of water molecules within its solid structure.

For example, in its normal state, copper(II) chloride has two water molecules associated with it (blue compound).

  • Systematic name: copper(II) chloride dihydrate
  • Formula: CuCl2 · 2H2O

When the water molecules are driven off by heating, the resulting compound, is called anhydrous. Anhydrous: containing no water molecules