I would assume because he doesnt have a flat bottom flask with a ground glass joint on it.
That would be an awful lot like using a heating mantle… This way I get even heating and heat transfer. The liquid to solid heat transfer is so much better than solid to solid and it covers the entire surface area of the flask… I do have an erlenmeyer flask with a 24/40 joint on it but what would the point be?
@TheLostBiologist I think you read the title, looked at the first picture, and then posted your reply without really reading anything else… Mine doesn’t spin but it sure does recover alcohol, is under vacuum, and is significantly better than using a beaker on a hotplate.
If you’ve ever tested the temps across various points on a flask and in a liquid you are boiling under vacuum you will notice that the vacuum ‘freezes’ out the surface of evaporation. Heating from underneath is inefficient and causes hot spots and such. Stirring helps but you will notice it is super cold around the area of the flask the surface of the liquid stays. Putting heating tape around this area is helpful (or at least insulating it), but this is a fairly slick way to do a hot water bath that easily lets you stir at the same time.
Initially I wanted to have a stir bar in the beaker AND in the flask so it would be much more like a stationary roto, but I had trouble getting 2 magnets working properly (I think if I used the right sizes at the right distances I could make it work), and the temp of the water stayed super consistent regardless. The investment for the mixer/hotplate and the beaker are typical items you would have anyhow vs the roto which is really for just one thing.
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