1. Experiment 8: Gravimetric Analysis
(CHE116 Supplement Packet)
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2. Purpose of This Experiment
To use a chemical reaction and stoichiometry to determine the identity of an unknown sample
Work in groups of 2, each person does a trial of the same unknown sample
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3. Today in Lab
Use the scoop provided to remove solid material from the reagent bottle (the italicized procedure steps will not be done)
Each person in the group should work with a trial of the unknown sample
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4. General Approach to Experiment
The unknown sample will be either Li2CO3, Na2CO3, or K2CO3. These alkali metal carbonates are soluble in water.
Dissolve a portion of your sample in water.
Add in CaCl2 (aq) and mix well.
Filter to isolate the CaCO3 precipitate.
Dry and weigh precipitate, calculate moles CaCO3 formed.
Determine identity alkali metal carbonate by calculating g/mole of original unknown.
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5. Filtering Figure 8.1 in your lab manual details the technique of filtering
R.F. Schneider
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OhioStateChemistry
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6. Drying Oven Dry your filter paper and sample in the drying oven
Make sure you know which sample is yours. Pencil does not wash off
Use a crucible tong to carry the hot watch-glass
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7. Additional Comments
Data Table, line b, Mass of filter paper Weigh the empty filter paper after you have torn off the corner and marked it with pencil. Unknown number Make sure you record the number of your unknown
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