Take the 2-minute tour ×
Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers and students. It's 100% free, no registration required.

How should the water flow in your condenser? From the flask to the top of the condenser, or from the top of the condenser back to the flask? I could imagine both: flask to top will fill the entire condenser with water, because of the resistance of gravity, enlarging cooling area, or top to flask, because this will generate counter current exchange increasing heat flow, but then it is almost impossible to get a decent cooling surface without extreme water pressure.

This picture suggests the first.

Refluxing

share|improve this question

2 Answers 2

up vote 3 down vote accepted

In general the cooling water is attached according to the countercurrent exchange mechanism to maximize the efficiency. Of course this doesn't work well for the Liebig condenser you pictured, but you generally wouldn't use this kind of condenser for reflux anyway. The most common condenser for reflux is the Dimroth condenser which can be used for countercurrent exchange without any problems as the entry and exit of the water are both at the top of the condenser.

Here is an image from Arbeitsmethoden in der organischen Chemie (page 43) that shows where to attach the cooling water for different condenser types.

enter image description here

share|improve this answer

Water should always enter from the bottom of a condenser (the end closest to the flask) and exit from the top of the condenser. Doing it this way always insures that your condenser will be full of cooling water. If you set it up the opposite way, and if for some reason the rate of water flow into the condenser decreased and became slower than the rate of water exiting the condenser, then the condenser would not remain filled with water. If the reaction were unattended, this could cause problems. BTW, here is a link you might enjoy. It contains a lot of lab tips, including "how to hook up the water tubing to a condenser".

share|improve this answer
    
Yes, I thought that would be the case, but then I remembered counter current exchange and started to doubt. –  Jori Jun 25 at 17:58

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.