Final answer:
The structure CuSO4 · xH2O, known as copper(II) sulfate pentahydrate, contains five waters of hydration, as indicated by the notation '5' in CuSO4 · 5H2O.
Step-by-step explanation:
The number of waters of hydration in the structure CuSO4 · xH2O is indicated by the value of 'x'. In the case of copper(II) sulfate, 'x' is equal to five, indicating that there are five waters of hydration. This is why the compound is referred to as copper(II) sulfate pentahydrate, meaning that each formula unit of copper(II) sulfate is associated with five water molecules. Hydrates are important to study because they have distinct properties from the anhydrous form of the compound and play a significant role in many chemical reactions and applications.