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Author: Subject: Is sodium acetate hygroscopic?
Foeskes
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[*] posted on 3-3-2018 at 17:35
Is sodium acetate hygroscopic?


So I made sodium acetate trihydrate by reacting glacial acetic acid and sodium hydroxide and boiling until a thin layer of the salt starts forming on the surface and I let it cool and scraped the crystal into paper towel and let it absorbed overnight. Next morning it was nothing more than a pool of slightly viscous sodium acetate solution.
I thought it wasn't hygroscopic.
do I have to use a desecator?

[Edited on 4-3-2018 by Foeskes]
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Eddygp
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[*] posted on 3-3-2018 at 17:48


Not only is it hygroscopic; it is deliquescent. This means it will absorb so much water vapour from the air, even at non-100% humidity, that it will dissolve in it!



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Foeskes
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[*] posted on 3-3-2018 at 18:17


I put it in desecator and pulled a slight vaccum, will it work.
Note: it's a thick glass cookie jar with a acrylic top and a silicone gasket, and my pump is a crude modified car tire inflator, I am also using silica gel as the desecator.
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JJay
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[*] posted on 3-3-2018 at 19:49


I have wondered if sodium acetate would be a good desiccant for acetic acid....



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clearly_not_atara
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[*] posted on 3-3-2018 at 20:04


Sodium acetate also binds to acetic acid, forming sodium diacetate.



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XeonTheMGPony
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[*] posted on 4-3-2018 at 05:14


Not that I have noticed I have a larg block of it sitting open to atmosphere for well over half a year, sure it absorbed some moisture but no where enough to liquefy it lol, think buddy there miss-thought and quoted for hydroxide.

some point I'll be dehydrating it to make glacial acetic acid
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Foeskes
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[*] posted on 4-3-2018 at 06:23


I was really wet and pretty much a gel maybe the water content was enough to dissolve it or something.
The pH was and still is neutral.
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XeonTheMGPony
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[*] posted on 6-3-2018 at 04:04


I purified mine and filtered it then ruff dried it, and there it has sat for all most a year open to atmosphere and not once has it gelled or been moist to touch.

I recrystallize in methanol then filter out any impurities that do not dissolve then, recrystallize and filter, then wash with ice cold methanol.

I then distill the depleted mother liquor to recover fresh batch of methanol for the next run.

Product is pure white fluffy crystals of high purity.
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weilawei
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[*] posted on 6-3-2018 at 06:06


XeonTheMGPony, I'll have to try recrystallizing from methanol. I just finished a small run making sodium acetate trihydrate from vinegar and NaOH, but the yield was pretty slight (5.04g). I think I lost a good deal of product (4/5 of it roughly) in the recrystallization due to its extreme solubility in water. I kept the mother liquor, so I'll see what else I can get out of it.
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