Lab # : % Composition of a Hydrate

Problem/Objective: To calculate the % composition of the water molecules attached to the hydrate and to convert the hydrate to an anhydrate.

Hypothesis: When the hydrate is heated, the water will evaporate, allowing you to calculate the % composition of the water molecules attached to the hydrate by removing the water; the will convert to an anhydrate.

Materials: 1. Empty evaporating dish2. Scale3. 1 g CuSO 5HO

Reaction: CuSO 5HO CuSO + 5HO

Experiment:

1. Record the data you collect in the data table.2. Determine the mass of an empty evaporating dish & record.3. Add approximately 1 gram of CuSO 5HO to your evaporating dish and re-weigh.4. Heat the evaporating dish and its contents strongly for approximately 10 minutes.5. Let the evaporating dish cool for 3 minutes, then weigh your evaporating dish and record its mast. 6. Wash out your evaporating dish with water (watch what happens) and clean up your lab station. 7. Determine the mass of your hydrate. (blue compound with HO)8. Determine the mass of your anhydrate. (blue compound without HO)9. Determine the mass of the water that was lost from the hydrate.Data/Observations:

Mass of evaporating dish48.9 g

Mass of evaporating dish + hydrate49.9 g

Mass after heating (dish + anhydrate)49.4 g

Mass of anhydrate0.5 g

Mass of hydrate1 g

Mass of water lost0.5 g

Analysis: 1. Accepted % of water:

5HOx 100 = 36% (90/250 * 100) CuSO 5 HO

2. Measured % of water

water lostx 100 = 50 % (0.5/1 * 100) hydrate

3. Calculate your % error using calculations #1 and #2.% error = measured value-accepted value accepted value x 100

(50-36)/36 x 100 = 39%

Conclusion: (work attached)

1. What must be done to the hydrate to convert it to the anhydrate?The hydrate must be heated, evaporating the water. When there is no water, it is an anhydrate.

2. Determine the molecular mass and % composition of the following:

a. %O in PO=56%Gfm=142 g/molb. %S in NaSO=41%Gfm=158 g/molc. %H in Cu(OH)=2%Gfm=98 g/mold. %HO in BaCl * 2HO= 15%

Gfm=243 g/mol

e. %N in NHNO=35%Gfm=80 g/mol

f. %S in Al(SO)= 28%Gfm=342 g/mol