Science Fair Project Encyclopedia
Thymolphthalein
Thymolphthalein is an acid-base (pH) indicator. Its transition range is at approximately pH 9.3-10.5. Below this pH, it is colorless; above this pH, it is blue. Its molecular formula is C28H30O4.
It can be used to make a disappearing ink. Dissolve the thymolphthalein in alcohol solution and add sodium hydroxide (NaOH) dropwise until it turns blue. It can then be sprayed onto cloth. After several minutes, it will turn colorless. (Carbon dioxide from the air will react with the basic solution. When the pH drops below 9.3, the thymolphthalein turns colorless.)
Last updated: 10-11-2005 16:23:06
10-26-2009 08:16:03
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details


