Molar Mass Lab
3.09 Molar Mass of Compounds
The purpose of this experiment is to determine the formula of a copper sulfate hydrate by heating it up. Materials:
Hydrate, crucible, balance, Bunsen burner and scale
First you measure the mass of the empty crucible and record that mass. Then you should fill the crucible with 3-5 scoops of the hydrate and record that mass as well. Heat the hydrate filled crucible above the Bunsen burner for 10 minutes for all f the water to evaporate. Let the crucible cool and then mass the crucible dehydrated solid inside. Record that mass and finally calculate the formula of the hydrate.
Data and Observations:
Mass of empty crucible
Mass of crucible and hydrate
Mass of hydrate
Mass of crucible and dehydrate
Mass of dehydrate
1. Obtain the mass of the empty crucible. Obtain the mass of the crucible and the hydrate. Subtraction of the mass of the empty crucible from the mass of the hydrate and crucible gives the mass of the CuSO4 hydrate. -20.97 grams
2. Heat the hydrate. After heating, record the mass of the crucible and the dehydrated compound. -20.44 grams
3. Subtracting the mass of the empty crucible from the mass of the crucible and dehydrated CuSO4 gives you the mass of the dehydrated compound. -0.94 grams
4. Subtract the mass of the dehydrated compound from the mass of the hydrate to determine the mass of water that was present in the hydrate. -20.03 grams
5. Convert the mass of water to moles of water.
6. Convert the mass of dehydrated compound to moles of the compound. -1.113
7. Divide by the lowest mole value to get a whole number mole ratio. -0.007
Discussion and Conclusion:
1. How would you expect the final measured mass of the anhydrate to change if the hydrate was not heated for a sufficient length of time, and why? -It would’ve still been wet causing it to weigh more...
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