This is a great lab to introduce or reinforce percent composition and empirical formulas. Students dehydrate copper (II) sulfate pentahydrate in a crucible or evaporation dish and use their data to determine the % composition and the number of water molecules per formula unit of copper (II) sulfate.
Why purchase my version of this lab? I give you teacher set up instructions, a key, and sample calculations. The lab has an introduction to help students understand why they are doing the lab. The data table drives the analysis in a linear and understandable fashion.
Your students will like this chemistry lab. Copper II sulfate crystals are a lovely aqua blue color that fades as the water is driven off. At the end, you can add water to a sample of the anhydrous salt and see the blue color return. The error for this activity tends to be very low so that it actually illustrates what chemistry teachers want it to illustrate and it's easy to determine the error (they didn't heat it long enough or they put a hot dish on the balance).
Keywords: stoichiometry, percent composition, empirical formula, chemistry, anhydrous, dehydrate, hydrate, mole, mass, molar mass, formula unit, gram formula weight, experiment, lab, laboratory.