(i) Assume that CuSO₄ + H₂O was the reaction that happened in that dish. Copper sulfate is anhydrous, so if water is added, it becomes copper sulfate pentahydrate.
CuSO₄(s) + H₂O(l) = CuSO₄ · 5H₂O(s)
Copper sulfate is soluble in water, so copper and sulfate both become aqueous. Copper sulfate has become crystallized, and the water has become attached to it.
(ii) As seen in my equation of (i), all that is left in the dish is a solidified, blue crystallized version which has a octahedral molecular geometry.
