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Topic: Find Ka of an indicator  (Read 7555 times)

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Offline diane

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Find Ka of an indicator
« on: June 07, 2013, 06:19:31 PM »
What is the Ka of thymolphthalein indicator?

The indicator has a range of pH's so how can I find the Ka?

Offline Borek

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Re: Find Ka of an indicator
« Reply #1 on: June 08, 2013, 03:18:00 AM »
http://www.titrations.info/acid-base-titration-indicators-preparation

Color changes in a pH range, but pKa is a single number, see discussion here:

http://www.titrations.info/acid-base-titration-indicators

pKa determination doesn't depend on the fact you are dealing with an indicator, all that matters is that you are dealing with a weak acid (or base).
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