Answer to Question #189328 in General Chemistry for Mohammed

Question

A 2.815 g sample of CuSO4•XH2O was heated until all of the water was

removed. Calculate the percentage of water of hydration and the formula

of the hydrate if the residue after heating weighed 2.485 g.

Answer 1

2.815 g – 2.485 g = 0.33 g of water loss

Now, dividing the mass of the water lost by the mass of hydrate used is equal to the fraction of water in the compound. Then multiplying this fraction by 100 gives the percent water in the hydrate.

(0.33 g / 2.815 g)(100) = 11.72 or 12%