My question is about the condenser used in a Soxhlet extractions. It's unusual looking compared to the rest of condensers, used in distillation for example, I've noticed it has a thin and short tube on top and my question is, do one leave it open when performing a Soxhlet extraction or should it be stopped with a stopper or something?

  • $\begingroup$ The condenser is open at the top. That is why it is important not to leave the apparatus unwatched. There have been many fires started from the ether overflowing and being lit from the heater. $\endgroup$ – LDC3 Nov 1 '14 at 14:02

First thing, you should NEVER perform any heated reaction with a stoppered condenser. You shouldn't even be allowed to work independently in the lab if this rule is not coming automatic to you. I am not sure what you mean by a special condenser being used in Soxhlet extractions. You can use any condenser that fits. Since you don't do a distillation you can use a shorter condenser so your whole Soxhlet set-up has a reasonable height.

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  • $\begingroup$ Very true, one thing I have noticed with soxhlet extractions is that when the liquid drops into the flask at the bottom it can suddenly cool down the flask at the bottom. This will make the vapour / gas volume inside the glassware greatly contract. So the volume of gas which enters and leaves via the top of the condensor can be very large compared to the amount which goes in and out of a condensor being used to reflux something in a round bottomed flask. As a result it is even more important not to heat a sealed soxhlet extraction than a "reflux". $\endgroup$ – Nuclear Chemist Apr 15 '18 at 19:59

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