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morganbw
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[*] posted on 7-8-2018 at 11:31
heating mantle size


okay gentlemen, please help me understand if I need a heating mantle for each size flask. This is a serious question as I am going to purchase at least two inner liner elements in a day or two. I just wonder on the benefit of having a different size for each size of glassware?
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Hendrik
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[*] posted on 7-8-2018 at 11:35


A heating mantle is necessary for distillations. You'll need only one heating mantle. I suggest buying one with a capacity of 500 ml. Those are cheap, but if you need more, buy a 1 liter one. Make sure all of your distillation flasks have the capacity of the heating mantle. If you choose to buy a 500 ml one, make sure your RBFs also have 500ml in order to fit inside the mantle.
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CobaltChloride
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[*] posted on 7-8-2018 at 12:32


I am able to use my 500ml heating mantle for heating 250ml round bottom flasks. Generally it is considered that a heating mantle works bests with appropriately sized flasks, but it can be used, albeit at a lower efficiency, with flasks half the appropriate volume.
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MrHomeScientist
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[*] posted on 7-8-2018 at 12:42


Do you leave an air gap, or fill the space with some kind of media? I seem to recall someone once filled theirs with sand and it damaged the mantle beyond repair due to overheating.
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Sidmadra
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[*] posted on 7-8-2018 at 13:25


I actually never use heating mantles unless I am using my 3L flask, which I rarely use anything that big. The largest flask I tend to use is my 1L RBF.

What I do as a makeshift heating mantle is take some aluminum foil, make a cup shape, and fill it with a small quantity of activated charcoal chips. Just enough to create a sort of nested shape to sit the RBF flask on. I then just set this on the hotplate. I find this conducts heat perfectly for pretty much all distillation applications, even very high temperature ones, or at least I've yet to run into any problems. It is also easy to clean up if any spills. It is necessary to use a clamp to hold the RBF in place so it doesn't tip, which may not be an issue when using a heating mantle.

This is great because my little aluminum foil / activated charcoal nest is effortlessly adapted to any reasonable flask size without even having to add any additional charcoal, and it does not inhibit stirring in any manner whatsoever. I prefer this set up any day over any sort of sand or oil bath.


I will say however that I prefer to use "flat bottom" round flasks for almost all my reactions that do not require being put under vacuum. Flat bottom round flasks are highly underrated in my opinion.

[Edited on 7-8-2018 by Sidmadra]
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DavidJR
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[*] posted on 7-8-2018 at 13:48


Quote: Originally posted by Sidmadra  

I will say however that I prefer to use "flat bottom" round flasks for almost all my reactions that do not require being put under vacuum. Flat bottom round flasks are highly underrated in my opinion.


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JJay
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[*] posted on 7-8-2018 at 14:23


500 mL and 3000 mL are good sizes for heating mantles. You can usually get away with a heating bath if you don't have the right size heating mantle. I use my 3000 mL a lot, and I could even see going with something slightly larger. In general, you can do a reaction or distillation with a flask that is from 1/10 to 1/2 of the volume of what is in it. You can usually get away with filling the flask more than half full, but it's not recommended, and if there is likely to be a lot of foam, half full may be too full.

I do not have a 1 L heating mantle, but that is obviously a good size if you have to pick just one. If heating mantles were really cheap, I'd get one for each size of flask.

I think most professional chemists prefer round-bottom flasks, but NurdRage and some other well-respected chemists definitely like jointed Erlenmeyers.

[Edited on 7-8-2018 by JJay]




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morganbw
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[*] posted on 7-8-2018 at 14:55


I have just ordered a 1000ml size element as well as a 500 ml size.
Much of what I will be doing will be with a water or an oil bath for a more controlled heat.
I am not in love with the heating mantles/hotplates/oil-water baths over any other things. I just wish to give the very few reactions that I actually do a chance.
I have the round bottom flasks and at present, the 1000ml is my largest. When I can actually get my stuff, to work better, I may go larger.


[Edited on 7-8-2018 by morganbw]
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