How do I find the mass of anhydrous salt and water in this compound?

A 5.00g sample of MgSO4 - 7H2O was heated until all the water was released from the hydrate. I wasn't in school and didn't learn it. Please answer ASAP.


If you have 5.00g of magnesium sulfate heptahydride, then the mass of anhydrous salt is the mass you have left after you release the water via heating, and the mass difference between the original and what is left is the mass of the water.


If you had 5.00g, and you have 3.87g after you finish heating, then you have 3.87g of anhydrous salt and 1.13g of the original hydrous salt was water.