A hydrated form of copper sulfate (CuSO4·x H2O) is heated to drive off all the water. If we start with 9.38 g of hydrated salt and have 7.01 g of anhydrous CuSO4 after heating, find the number of water molecules associated with each CuSO4 formula unit.

Question

jfraser · Answer

heating a hydrate drives off the water, but leaves the salt behind. Use the mass differences to find:

1) the mass of water lost
2) the MOLES of water lost (using Molar Mass of water)
3) the mass of dry salt left behind
4) the MOLES of dry salt (using Molar Mass of the dry salt)

5) find the RATIO $\frac{moles H_2O}{moles salt}$ and you'll get the number of water molecules associated with each formula unit of salt