If you dissolve hydrate, such as CuSO4∙5H2O, does the 5H20 leave?

Question

If you have a hydrate, such as CuSO4∙5H2O, and you dissolve it in water to create an aqueous solution, where does the 5H2O go? Does it stay in the formula, or dissolve into the water as well to become 5H2O (l) and CuSO4(aq)?

Answer 1

The .5H2O is just a waters of hydration that forms part of a stable crystal structure. You can get 1,2,3, etc. but the structure is satisfied with 5. Putting the compound into water removes the crystal structure and places the compound into a dissociated Cu++ and SO4- - species.

Answer 2

The Wiki reference below has an excellent summary of your question.

The answer is that the water just joins the rest of the dissolving water (they use the term labilized, from "labile" meaning movable or constantly changing).

Quote:
For many salts, the exact bonding of the water is unimportant because the water molecules are labilized upon dissolution. For example, an aqueous solution prepared from CuSO4•5H2O and anhydrous CuSO4 behave identically.

Therefore, knowledge of the degree of hydration is important only for determining the equivalent weight: one mole of CuSO4•5H2O weighs more than one mole of CuSO4.

In some cases, the degree of hydration can be critical to the resulting chemical properties. For example, anhydrous RhCl3 is not soluble in water and is relatively useless in organometallic chemistry whereas RhCl3•3H2O is versatile.
END QUOTE

Answer 3

Yes and no (LOL). The hydrate is Cu(H2O)4 2+ + SO4= plus one water of crystallization. When you dissolve it in water, the fifth H2O leaves, but the species in solution is still Cu(H2O)4 2+. There is no 5H2O(l) nor CuSO4(aq

Answer 4

No. It is still a hydrate. If you dissolve the copper sulfate pentahydrate in H2O and then evaporate the H2O you will still have copper sulfate pentahydrate