How to determine molecules of water in hydrated salt?

Question

I have lost the lab manual where it tells how to obtain the # of H2O molecules (X) (ex. CuSO4 - X H2O)
Details on experiment:
Weighed sample of hydrated copper sulfate crystals, added it to distilled water and while stirring , added 1 drop of sodium carbonate solution until a precipitate was visible. Then added drops of acetic acid while stirring until the precipitate disappeared.

titrated this with Sodium Thiosulfate solution with a potassium iodide indicator.

now i have all the experimental values of titration etc.. but no idea how to obtain the X (H2O)

thanks in advance for the help

*need to obtain experimental value of hydration* i already know the usual is pentahydrate :P

Answer 1

I suggest you just read the label on trhe reagent bottle. It will probably tell you the CuSO4 has five waters of hydration. You know Cupric Sulfate "Pentahydrate" should tell you something.

Answer 2

You can't just look at the solid and know how many waters of hydration are present in the crystals.

Answer 3

You know the mass of CuSO4.xH2O

You know the moles Cu from your titration.

Mass = moles x formula weight

Eeach CuSO4.xH2O gave you one Cu2+ in solution, so formula weight is for CuSO4.xH2O

What isn't CuSO4 in this is xH2O; each H2O contributes 18.0