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Recrystallizing out of methanol

by scienceboy2000
Tags: methanol, recrystallizing
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Nov13-13, 01:50 PM
P: 7
Hi, I am trying to recrystallize salt from methanol. I am having trouble. This is exactly what I did:

I dissolved a gram of salt into 20 ml of methanol (the bottle I have says methyl hydrate but I read online that it's the same thing as methanol). Then I made a hot water bath. I put a pyrex dish into a pot of boiling water. Using an eye dropper, I dropped a few drops into the pyrex beaker. I expected the methanol to evaporate almost immediately, leaving me with a thin flakey crystal that can easily be scraped off. But at best, I am left with a small piece of crust that is impossible to scrape off the pyrex dish. What is wrong?
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Nov13-13, 03:19 PM
Borek's Avatar
P: 23,594
No idea why you expected dried out substance to easily separate from the glass. It may, but it doesn't have to.
Nov13-13, 04:15 PM
P: 383
What are you planning on getting out of this process? It seems to me that you are just spinning your wheels. Making a solution and evaporating the solvent leaves you with the material you started with minus some time and energy.

Recrystallizations are typically done to purify something from a mixture and requires either some background knowledge of the system (what your compound is, what impurities might be there etc) or a bunch of trial and error.

See Wikipedia for a intro discussion: Recrystallization

Nov14-13, 10:42 PM
P: 7
Recrystallizing out of methanol

Thanks for the replies! I have read a lot about crystallization and I will be doing some experiments over the next couple of days. I will update this thread if I have any questions.

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