# Hydrate Lab

Topics: Crystal, Water, Chemistry Pages: 2 (434 words) Published: December 5, 2012
Pre Lab
1a. Hydrated compound: ionic compound which contain water molecules inside their crystal lattice. The water is not chemically bonded to the crystal in any way and can be extracted by heating the compound. 1b. Anhydrous compound: a compound without water.

2a. The dot means that there are water molecules present in the crystal lattice in a specific ratio. 2b. For every mole of copper sulfate, there are five moles of water. 2c. The molar mass of copper (II) sulfate is 159.61 grams/mol 2d. The molar mass of 5H2O is 90.10 grams/mol

2e. The molar mass of the entire compound is 159.61 + 90.10 = 249.71 grams/mol 2f. The percent of water in the compound is mass of water/mass of compound = 36% Mass of crucible before heating| 40.00 grams|

Mass of crucible + hydrate before heating| 41.38 grams|
Mass of crucible + anhydrate after 1st heating| 41.08 grams| Mass of hydrate| 1.38 grams|
Mass of anhydrate| 1.08 grams|
Mass of water| .2 grams|
Formula of anhydrous salt| Cu(SO4) – Copper Sulfate |
Data Table

Calculations
1. Mass of hydrate = 1.38 grams. Mass of anhydrous = 1.08 grams. Mass of water = .2 grams. 2. Ratio of anhydrous mass to hydrate mass is 5.4.
3. Moles of anhydrous salt: 1.
4. Moles of water are five moles.
5. Moles of water per mole of anhydrous salt was about 5.4/1 ratio but really is 5/1 6. Empirical formula for hydrate is Cu(SO4) * 5H2O
Conclusion
The mass of the anhydrous salt depends on the mass of the hydrate because the crystal lattice is a fixed ratio of the salt and water. This experiment essentially proved that by heating a crystal which contains water in its lattice structure, water can be extracted resulting in only the salt in a changed color. Our salt changed from blue to white upon heating it. Since our laboratory is not under perfect conditions, there are several sources of error. Human errors included incorrectly registering the mass of the salt or accumulation of left over salt...