To determine the percentage of water in a hydrate and determine the number of water molecules in each hydrate.
To determine the empirical formula of the hydrate and name each.
Hydrate, porcelain crucible, crucible tongs, ring stand, iron ring, pipe stem triangle, wire gauze, Bunsen burner set-up, and electronic balance.
1. Set up the heating apparatus as demonstrated.
2. Mass the empty crucible. Record observations.
3. Mass between 1.00 g and 1.25 g of hydrate. Record observations.
4. Heat the crucible and its contents gently for 2 minutes and then more strongly for 3 minutes longer.
5. Mass the crucible and its contents and record the mass of the 1stheating.
6. Transfer the crucible back to the heating apparatus and heat strongly for 3 minutes.
7. Mass the crucible and its contents and record the mass of the 2nd heating.
8. If the difference in mass between 1st and 2nd heating is greater than 0.03 grams, repeat steps 7-9 to obtain a mass of the 3rd heating.
9. After you have completed the data collection, use a dropper to add water back into the anhydrous salt. What do you observe? Is the reaction endothermic or exothermic?
10. Rinse your product into the waste beaker. Rinse thoroughly, then heat with the Bunsen Burner.