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Topic: How do you measure a molecule's pka?  (Read 1700 times)

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Offline ashika

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How do you measure a molecule's pka?
« on: December 10, 2014, 09:59:49 AM »
Hello everyone,

I'm trying to measure the pka of a small molecule in water. I dissolved some of this molecule in a sodium phosphate buffer solution of pH 7.3. and proceeded to adding HCl 0.1 M. I obtained asigmoid curve the point of inflection of which occurs at pH 4.6. Can I say that 4.6 is the pKa of my molecule is 4.6? Can you titrate pKa in a buffered solution? Should I redo my experiment in distilled water?

Thanks!
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Offline Babcock_Hall

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Re: How do you measure a molecule's pka?
« Reply #1 on: December 10, 2014, 10:42:53 AM »
There are others here with greater expertise, but I am concerned about the presence of phosphate buffer.  I would try again in DI water.
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Offline Irlanur

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Re: How do you measure a molecule's pka?
« Reply #2 on: December 11, 2014, 10:15:56 AM »
why would you do that in buffer?
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