Are there any other forms of Copper Sulfate Pentahydrate? Can it have more or less water molecules attached?
anhydrous copper (II) sulfate = dry version
copper (II) sulfate pentahydrate = wet
Copper (II) sulfate can exist in a dry or wet state.
On the left of the image you can see the hydrate (wet) version of copper sulfate and on the right the anhydrous (dry) form.
In the lab you can heat a sample of copper sulfate to dry it, forming anhydrous copper sulfate. You will notice the compound becoming more white in appearance as it dries. Adding water will cause the color to change back to a blue color is the compound switches back to the hydrated version.
A common stoichiometry lab involves heating a sample of copper (II) sulfate pentahydrate and determining the change in mass. This allows for a calculation of the empirical formula of the hydrate.
Hope this is helpful.