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Topic: Question about solubility and crystallizing  (Read 4496 times)

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Offline curiousgeorge1234

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Question about solubility and crystallizing
« on: September 25, 2007, 08:11:47 PM »
When a compound is being tested for solubility it is put in a solvent and heated.  When cooled slightly sometimes crystals form and sometimes they don't.

I am wondering why sometimes crystals do not form.  Is it just that the solution may be too warm still, or there was too much solvent? 
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Offline Bakegaku

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Re: Question about solubility and crystallizing
« Reply #1 on: September 26, 2007, 12:02:02 AM »
It could be either of those, or sometimes the crystals don't have a nucleus around which to form and the solution becomes supersaturated.  You need more information.
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Offline curiousgeorge1234

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Re: Question about solubility and crystallizing
« Reply #2 on: September 26, 2007, 02:37:21 PM »
Regarding crystals, I mixed anthracene with ethanol and it appeared that it was not soluble.  However, what I've read online is that it IS soluble in ethanol.

Where can I find out what should really happen?
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Offline agrobert

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Re: Question about solubility and crystallizing
« Reply #3 on: September 26, 2007, 06:21:17 PM »
anthracene is soluble in some alcohols. think about the structure and polarity of anthracene? are there better solvents for crystallization?
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Offline curiousgeorge1234

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Re: Question about solubility and crystallizing
« Reply #4 on: September 26, 2007, 09:56:28 PM »
I would think anthracene would not be soluble in ethanol, but would be in hexane for example - based on structure alone.  Would that be right?
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Offline agrobert

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Re: Question about solubility and crystallizing
« Reply #5 on: September 26, 2007, 10:06:28 PM »
I haven't tried it but I would assume that ethanol is too polar.  Longer chain alcohols may be better.  Have you thought about binary systems?
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