Hydrates Lab
By - Hamzah , Ethan and Ivan
Introduction
A hydrate is a compound that contains water molecules within its crystalline structure. When a hydrate is
heated, the water molecules evaporate, leaving behind the anhydrous compound. By measuring the mass
before and after heating, we can determine the amount of water that was originally present in the hydrate.
This allows us to calculate the mole ratio of water to the compound and determine the empirical formula
of the hydrate.
Purpose
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To convert copper(II) sulfate hydrate to anhydrous copper(II) sulfate through heating.
To determine the percent composition of water in a hydrate of copper(II) sulfate.
To determine the chemical formula of CuSO4 · xH2O
Materials
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Bunsen Burner
Flint lighter
Hydrated salt (CuSO4 . xH2O)
Electronic balance
Scoopula
Test tube tongs
Test tubes
Safety
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Handle hot equipment carefully to avoid burns
Tie back long hair and secure loose clothing
Keep the test tube pointed away from yourself and others
Wash your hands after handling the chemicals
Procedure
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The mass of the empty test tube was measured and recorded.
Approximately 1.00 grams of Hydrous Copper (II) Sulfate was added to the test tube and
recorded.
The sample was heated with the Bunsen burner
The test tube was allowed to cool.
The mass after heating was measured.
The heating and cooling process was repeated until a constant mass reading was achieved.
Table of mass observations
Measurements
Mass (g)
Mass of an empty test tube
18.44 g
Mass of test tube + hydrate
19.44 g
Mass of test tube + CuSO4
19.07 g
Mass of CuSO4
0.63 g
Mass of water lost
0.37 g
Calculation
Moles of H2O 0.37 𝑔
18.0 𝑔/𝑚𝑜𝑙
= 0.0206 mol
Moles of CuSO4 0.63 𝑔
159.6 𝑔/𝑚𝑜𝑙
= 0.00395 mol
Mole ratio CuSO4
0.00395 / 0.00395 = 1
H2O
0.0206 / 0.00395 = 5.2
Ratio
1:5
∴ The Empirical formula is CuSO4 . 5H2O
Sources of error
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Not all water is removed after heating
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Inaccurate measurements
Moisture in the air
Overheating
Loss of material due to heating and handling
Conclusion
Heating the copper (II) sulfate removed the water from its crystalline structure, leaving behind anhydrous
CuSO4. The mass difference before and after heating was used to calculate the amount of water in the
hydrant. After converting the masses to moles, the empirical formula of the hydrate is approximately
CuSO4 · 5H2O.