One molecule of hydrated CuSO4 contains 5 molecules of water of crystallization.
Water of crystallization is the fixed number of molecules of water contained in one salt formula unit. Or we can say the water is stoichiometrically crystal bound. Crystal salts with water of crystallization are known as hydrates. The other names of water crystallization are crystallization water or water of hydration.
The most common form of copper sulfate is its pentahydrate, given by the chemical formula CuSO4.5H2O. This form is characterized by its bright blue colour. However, it can be noted that the anhydrous form of this salt is a powder that is white.