# sci/chemistry

when 1.87 g of gypsum(hydrated calcium sulfate) was heated to constant mass, it lost 0.39 g of water. What is the formula of gypsum?

YOu know it is of the form: CaSO4.XH2O

the idea here is to find x.

calculate the number of moles of water in .39g.

Calculate the number of moles of CaSO4 in 1.87-.39 g.

divide the moles of water by the moles of CaSO4. That is x

Now, the lesson: Why is this so?

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