The Percent Water in Magnesium Sulfate Heptahydrate
Introduction:
Many ionic compounds may appear to be dry, yet when heated yield large
quantities of water. Such compounds are called hydrates. An example is
MgSO4 • 7H2O. This means for every 7 moles of H2O there is 1 mole of MgSO4.
If the water is removed from the hydrate, it is said to be anhydrous.
Purpose:
To perform an experiment which will allow us to calculate the percent of water in
Magnesium Sulfate Heptahydrate (Epsom Salt) both experimentally and
theoretically, and to calculate the percent error.
Theory:
MgSO4 • 7H2O(s) + Heat  MgSO4(s) + 7H2O(g)
Hydrate
+ Heat  Anhydrous
Procedure:
1.
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Data Table:
Find mass of crucible.
Place about .5 grams of MgSO4 . 7H2O in the crucible. Find the mass and
record in a data table in your lab book. Don’t forget units!!
Set up Bunsen burner, ring and triangle.
Heat crucible gently until the MgSO4 . 7H2O(s) turns clear to a white solid.
Allow the crucible to cool to room temperature and find the mass of
remaining MgSO4.
Clean up your lab station by placing remaining MgSO4 in the garbage.
Make your calculations.
(Make your own.)
Calculations: (Show your work.)
THEORETICAL DATA
Molar Mass of 7H2O
Molar Mass MgSO4 • 7H2O
Theoretical percent of H2O in MgSO4 • 7H2O
EXPERIMENTAL DATA
Mass of MgSO4 • 7H2O
Mass of MgSO4
Mass of H2O
Experimental percent of H2O in MgSO4 • 7H2O
Percent Error
Conclusion:
Using complete sentences, state your results and explain any errors you could
have made in lab.
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