isky
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Registered: 18-4-2005
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Basic steam distillation information.
Hi there, i'm glad to be here. 
I'm very new to chemistry, i'm tring to understand how steam distillation works, as i don't know too much about chemistry i'm
searching for some easy examples. For ex:
A .pdf file that teach you how a distillation setup works (whit photos so i can see it) how a conderser works and how it's connected, etc, etc...
Thanks you.
isky.
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Magpie
lab constructor
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Mood: Chemistry: the subtle science.
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Isky,
Steam distillation is really very simple - I have done several of them for class assignments. It works on the principle of using steam to codistill a
substance that is water immiscible. Even though that substance may have a high boiling point it will codistill over with water at a temperature below
100 C. This is due to the addition of the pure component vapor pressures to equal atmospheric pressure (usually ~ 760 mm Hg).
Any good organic chemistry lab manual will explain it fully and provide sketches of the equipment set up.
The single most important condition for a successful synthesis is good mixing - Nicodem
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neutrino
International Hazard
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The basic gist (sp?) of the process is very simple if you have some grounding in the process of distillation.
Any substance will have a certain vapor pressure at any given temperature (except absolute zero, of course.) Say you have an organic substance with a
vp of 25 mmHg at 100*C. This means that in a perfect vacuum at 100*C, the substance will evaporate a little and its vapor will exert a pressure of 25
mmHg on its container (note: 760 mmHg = 1 atmosphere). This is like water evaporating in below its boiling point.
If you pass steam over the substance, you will get a mixture of water vapor and a little bit of the vapor of your substance. Condense this and you
will have the same thing—water and a little of your substance. Drain off the water and you now have your purified material.
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