Before I tell you about the lab, ther first thing you need to know is what a hydrate is. A

**is a compound that has a definite number of water molecules incorporated into its crystal structure. The crystals appear dry, but when these compouds are heated strongly, water is given off, leaving the**

*hydrate**anyhydrous*form of the compound.

The first mass we found was the empty crucible. We weighed the crucible on a centigram scale. The mass my partner and I found was 25.23g. Then we found the mass of the crucible and the hydrate, which was 30.11g.

To find the mass of the hydrate alone, this is the formula:

Mass of crucible and hydrate - Mass of empty crucible = Mass of hydrate

30.11g - 25.23g = 4.88g

Next, we heated the crucible and anhydrous salt using a bunsen burner and weighed it again on the centigram scale. The mass we found was 27.79g. After that was found, we heated the same objects again for a second heating and came up with a mass of 27.78g

To find the mass of the anhydrous salt alone, this is the formula:

Mass of the first heating - Mass of the empty crucible = Mass of anhydrous salt

Lastly, to find the mass of the water given off, this is the formula:

Mass of the hydrate - Mass of the anhydrous salt = Mass of the water given off

**ANALYSIS OF RESULTS**(whopee)

1. Calculate the percentage of water in a hydrate

%H20 = 2.33g

---------- x 100% = 47.7%

4.88g

2. Calculate the number of moles of the anhydrous salt left behind.

2.55g x 1mole

--------------- = 0.02 mol

120.4g/mol

3. Calculate the number moles of water removed by heat from your sample of hydrate.

2.33g x 1 mol

----------- = 0.13 mol

18g/mol

4. Calculate the moles of water per mole of the anhydrous salt.

0.02

------ -> 1

0.02

0.13

------ -> 7

0.02

5. What is the empirical dormula of the hydrate?

AB .

**7H2O**