A sample of a hydrate of CuSO4 with a mass of 250 grams was heated until all the water was removed. The sample was then weighed and found to have a mass of 160 grams. What is the formula for the hydrate?

CuSO4 * 10 H2O
CuSO4 * 7 H2O
CuSO4 * 5 H2O
CuSO4 * 2 H2O
CuSO4 * H2O

3 answers

I'd take the difference between the hydrated and dehydrated sample and then divide by the molar mass of one water molecule H2O. Like so:

(250 grams - 160 grams)/Molar Mass H2O

This will allow me to find out how many water molecules there were.

CuSO4 * 5 H2O

ur a butt