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Author: Subject: vacuum distillation
beastmaster
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[*] posted on 24-3-2010 at 12:31
vacuum distillation


Most you always have a small leak while doing a vacuum distillation so the distillates will come over, or will the distillates(vapor)behave the same in a vacuum as they do at atm. pressure. Coming over, condensing and dripping in the receiver flask? I keep getting conflicting information. Thanks
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Magpie
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[*] posted on 24-3-2010 at 13:25


The vapor will come over the same way, just at a lower temperature.

If you're thinking a sweep gas is necessary - it isn't.




The single most important condition for a successful synthesis is good mixing - Nicodem
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beastmaster
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[*] posted on 26-3-2010 at 21:26


thank you ,that answers my question. sweep gas. I didn't know the word, but that is what I wanted to know if it was needed or not.
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Arrhenius
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[*] posted on 27-3-2010 at 07:39


That being said, vacuum distillations are often much more behaved if you use a capillary ebullator tube. This lets a minute amount of air bubble through the distillation pot and generally reduces bumping without reducing your vacuum much.
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[*] posted on 1-4-2010 at 04:43


in the above case sometimes inert gasses are used to prevent oxidation, higher boiling inert miscible (or immiscible) substances can be charged into the distiling flask to prevent oxidation on distilling to dryness (to buffer heat) silicones for example. the gas stream has the added advantatage of sparging the distillation contents and increasing the rate of evaporation.
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