If 15.60g of a hydrated compound is heated in an oven for several hours, its mass drops to 8.63g. Assuming that the reduction in mass is due to the loss of water what is the percentage of water in the original hydrate?

In order to calculate the percent of water in the hydrate, we need to know the amount of water that is lost after heating. We simply subtract the initial amount and the final amount. We do as follows:

mass of water = 15.60 g - 8.63 g = 6.97 g

Percent water = 6.97 / 15.60 x 100 = 44.68%