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### Topic: Recrystallization amount?  (Read 9299 times)

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#### amoeba

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##### Recrystallization amount?
« on: September 14, 2005, 05:29:31 PM »
How any mL of boiling water would I need to crystallize 25g of phthalic acid?  Then if I cool the solution to 14 degree celsius how many grams of phthalic acid would crystallize?

I know boiling water has a solubility of 18g/100mL.
I know cool water has a solubility of 0.54g/100mL.

I'm just not seeing what I should do.  Any help would be much appreciated!

edit-changed 0.54g/mL to 0.54g/100mL
« Last Edit: September 16, 2005, 12:29:22 PM by amoeba »

#### dexangeles

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##### Re:Recrystallization amount?
« Reply #1 on: September 16, 2005, 02:29:02 AM »
in theory you can recrystalize all 14g, but you never will some stays in equilibrium and cause of experemental errors

are you talking about just enough boiling water? then cooling that water down? or supersaturating the solution more by more boiling?

#### mike

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##### Re:Recrystallization amount?
« Reply #2 on: September 16, 2005, 02:36:09 AM »
From the data you have provided you would need 138.8mL of hot water to dissolve 25g of phthalic acid.

If this was then cooled down there would be 0.75g of phthalic acid left in solution, leaving you with 24.25g of phthalic acid.

note: I am assuming that you meant to write 0.54g/100mL for the cold solubilty and not 0.54g/mL
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