Caffeine and Tea Bag Reuse


Other Science Fair Projects


Determine the rate of release of caffeine from a bag of normal tea.


If I drink too much caffeine I get the jitters. I now buy a high grade Dragonwells green tea. It makes up to three cups of good tasting tea. If I use the same tea bag to make three cups of tea, do I keep getting more caffeine, or does all the caffeine come out in the first cup?

Experimental Set up

You'll need a way to measure the caffeine in a sample of solution. I seem to remember that there is some way to precipitate caffeine out of solution. Ask your science teacher.

Bring distilled water to a boil. Measure out one cup. Drop in one tea bag for one minute. 

Remove the bag, and set it on a saucer. Do not squeeze it out.

Measure the caffeine.

Measure our one more cup of boiling water. Put the tea bag into it, be sure to pour in any liquid that is in the saucer. Wait one minute and remove the tea bag back to the saucer.

Measure the caffeine.

Do it again.

Repeat the sequence until you find no measurable caffeine released to solution.

Plot the results. (One chemist friend expects an exponential decay.)

Additional Questions:

Do black tea and green tea have the same decay curve?

How much caffeine is in Dragonwells tea Vs black tea?

If the tea bag steeps for two minutes, how does that change the result?

Good Dragonwells tea can make three cups of good tasting tea. What is the optimal time to steep the tea bag to get good tasting tea and a minimum of caffeine in one day?

Let me know what you discover!