More Composition of Hydrates 
Solve the following hydrate problems on notebook paper. Work neatly and show all work!!
1. Cerium (III) iodide occurs as a hydrate with the composition 76.3% CeI3 and 23.7% water. Calculate
the formula for the hydrate.
2. Lead(II) acetate exists as a crystalline hydrate that is 14.25% water by mass. What is the molecular
formula for this hydrate?
3. A 17.44 gram sample of a zinc sulfate hydrate is heated strongly in a crucible to drive off all water.
After heating the sample has a mass of 9.79 g. Calculate the molecular formula for this hydrate.
4. An empty crucible has a mass of 12.763 grams. The crucible and hydrate have a mass of 13.454 grams.
After heating, the crucible and anhydrous salt have a mass of 13.010 grams. What is the formula of this
hydrate of MgSO4 • ?H2O? Hint: take moles out to 4 sig figs
5. 11.75 g of a common hydrate of cobalt (II) chloride is heated, leaving 9.25 g of anhydrous cobalt (II)
chloride. What is the formula and name for this hydrate?
6. You are given an unknown hydrate of calcium sulfate. The following data was collected.
Mass of empty crucible
11.38 g
Mass of crucible & sample before heating 16.27 g
Mass of crucible & sample after heating 15.25 g
Calculate the empirical formula of the calcium sulfate hydrate.
7. Washing soda, a compound used to prepare hard water fro washing laundry is a hydrate of sodium
carbonate. When a 2.558g sample of washing soda is heated at 25 oC, all the water of hydration is lost,
leaving 0.948 g of anhydrous sodium carbonate. What is the empirical formula of the hydrate?
More Composition of Hydrates 
Solve the following hydrate problems on notebook paper. Work neatly and show all work!!
1. Cerium (III) iodide occurs as a hydrate with the composition 76.3% CeI3 and 23.7% water. Calculate
the formula for the hydrate.
2. Lead(II) acetate exists as a crystalline hydrate that is 14.25% water by mass. What is the molecular
formula for this hydrate?
3. A 17.44 gram sample of a zinc sulfate hydrate is heated strongly in a crucible to drive off all water.
After heating the sample has a mass of 9.79 g. Calculate the molecular formula for this hydrate.
4. An empty crucible has a mass of 12.763 grams. The crucible and hydrate have a mass of 13.454 grams.
After heating, the crucible and anhydrous salt have a mass of 13.010 grams. What is the formula of this
hydrate of MgSO4 • ?H2O? Hint: take moles out to 4 sig figs
5. 11.75 g of a common hydrate of cobalt (II) chloride is heated, leaving 9.25 g of anhydrous cobalt (II)
chloride. What is the formula and name for this hydrate?
6. You are given an unknown hydrate of calcium sulfate. The following data was collected.
Mass of empty crucible
11.38 g
Mass of crucible & sample before heating 16.27 g
Mass of crucible & sample after heating 15.25 g
Calculate the empirical formula of the calcium sulfate hydrate.
7. Washing soda, a compound used to prepare hard water fro washing laundry is a hydrate of sodium
carbonate. When a 2.558g sample of washing soda is heated at 25 oC, all the water of hydration is lost,
leaving 0.948 g of anhydrous sodium carbonate. What is the empirical formula of the hydrate?