[jasian]

I am growing copper (II) sulfate pentahydrate crystals and need to recover some of the copper (II) sulfate pentahydrate that I mixed in water. I do not fully understand hydration and rehydration. If I heat the solution to boil away water, will the copper (II) sulfate pentahydrate dehydrate to its anhydrous form?

If no: great

If yes: how do I rehydrate the crystals so that I can dissolve them in the same concentration as my initial solution?

[Borek]

If I heat the solution to boil away water, will the copper (II) sulfate pentahydrate dehydrate to its anhydrous form?

Not without roasting.

If yes: how do I rehydrate the crystals so that I can dissolve them in the same concentration as my initial solution?

In general most hydrates don't have stable composition and amount of water they hold changes with humidity. Whether it matters and whether the effect is important for measuring their amount depends on the application, sometimes you need to know the concentration with high precision in which case most hydrates are no go, sometimes you need a solution with concentration that is only approximate, and then using hydrates can be perfectly OK. Case by case basis.