Lab 1 - Caffeine Lab Report Guide
Date Submitted: Self-evaluation Score:. . . . . . . .
Lab Group Members: X
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The Lab Question: What percent of the weight of tea leaves is caffeine?
Our Hypothesis: X
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Research References:

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Procedures Observations
Caffeine, C8H10N4O2, is the most widely used drug in the world. It is both chemically and physically addictive. Caffeine occurs naturally in coffee, tea, and chocolate. It is slightly soluble in water at room temperature, but highly soluble in water at 100 oC. Chloroform is a nonpolar solvent in which caffeine is highly soluble. Using a combination of the polar solvent water and the nonpolar solvent chloroform, crystals of caffeine can be extracted from tea leaves.

Procedure, part 1:

  1. Weigh 15 grams of ground tea leaves.
  2. Boil the tea in 200 ml of water for 15 minutes.
  3. Allow to cool for 15 minutes.
  4. Remove the tea leaves and filter the solution.

Procedure, part 2:

  1. Add 100 ml of chloroform to the tea/water solution.
  2. Give the chloroform, which is more dense than water, time to settle to the bottom of the container. If an emulsion forms between the two layers, break it up with a stirring rod.
  3. After the chloroform has settled to the bottom of the container, decant the water and discard it.
  4. Filter the tea/chloroform solution to remove any residue.
  5. Set up a hot water bath in the fume hood and bring the solution to a boil. Chloroform boils at just over 60 oC. Be sure to keep the temperature just high enough to boil the chloroform.
  6. Evaporate the solution down to about 25 ml and remove it from the heat.
  7. Weigh a watch glass.
  8. Set up a hot water bath using a beaker that the watch glass will sit on top of.
  9. Fill the watch glass with the concentrated caffeine solution and evaporate it. Repeat this process until all the concentrated solution has been evaporated.
  10. Remove the watch glass from above the hot water bath and let it cool. Wipe the moisture from the bottom of the watch glass.
  11. Weigh the watch glass and caffeine.
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