. A hydrate of copper(II) sulfate, when heated, goes

Chapter 3, Problem 112

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. A hydrate of copper(II) sulfate, when heated, goes through the succession of changes suggested by the photograph. In this photograph, (a) is the original fully hydrated copper(II) sulfate; (b) is the product obtained by heating the original hydrate to 140 C; (c) is the product obtained by further heating to 400 C; and (d) is the product obtained at 1000 C. A 2.574 g sample of was heated to 140 C, cooled, and reweighed. The resulting solid was reheated to 400 C, cooled, and reweighed. Finally, this solid was heated to 1000 C, cooled, and reweighed for the last time. Original sample 2.574 g After heating to 140 C 1.833 g After reheating to 400 C 1.647 g After reheating to 1000 C 0.812 g (a) Assuming that all the water of hydration is driven off at 400 C, what is the formula of the original hydrate? (b) What is the formula of the hydrate obtained when the original hydrate is heated to only 140 C? (c) The black residue obtained at 1000 C is an oxide of copper. What is its percent composition and empirical formula?