rot
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Making anhydrous liquids with calcium chloride.
Hi all,
I know that you can make anhydrous acetone by adding calcium chloride to it, but will this also work with other liquids like ethanol?
this might be interesting because you can't make ethanol more concentrated then 96% by distilliation, because it forms an azeotrope with water at that
concentration.
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leu
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Calcium chloride forms complexes with many organic liquids such as acetone, so it's not as good of a drying agent as you think  This subject is covered quite thoroughly in textbooks such as Vogel's, you'll
undoubtedly find your answers more quickly by doing your own research 
Chemistry is our Covalent Bond
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chromium
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With some liquids it can be done, with ethanol as much as i know - no. Ethanol unites with calcium chloride just like water.
Liquids can be dried with CaCl2 (or other suitable salts) if they contain only small amounts of water. Otherwise one needs big volume of salt and
product is hard to separate from this mesh.
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vulture
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If you combine drying with distillation (that is put the salt in your boiling flask) you can get away with pretty weak stuff for drying your solvents.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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evil_lurker
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IIRC that when you heat your solvents with a salt in them you'd be drying the salt at the same time as the solvent... i.e meaning you'd be distilling
over some water too.
The proper way is to distill the solvent first to remove the majority of the water, use a drying salt to get most of the rest of what is carried over
azeotropically, then finish off to anhydrous by adding sodium/molecular sieves.
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The_Davster
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Would not that depend on the boiling point of the solvent and the temp at which the salt looses water? Distilling something that boils at 80 degrees
over a salt that looses water at 200C I cannot see as a problem. Just adding a bit more drying agent should prevent any problems.
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madchem
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Drying Agents
Here is something which is on topic and could help people chosing drying agents when working in the lab
sorry almost forgot
props to rhodium because this chart comes from you.
[Edited on 26-3-2006 by madchem]
Attachment: dryingagent.data.html (13kB)
This file has been downloaded 729 times
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neutrino
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| Quote: | Originally posted by rogue chemist
Would not that depend on the boiling point of the solvent and the temp at which the salt looses water? Distilling something that boils at 80 degrees
over a salt that looses water at 200C I cannot see as a problem. |
This is a steam-distillation type thing. If you pass steam over something with a low vapor pressure, the sheer quantity of steam flowing past will
pick up a good deal of the substance. Likewise a lot of solvent vapor passing over a water-rich drying agent will pick up a lot of water, assuming
that the water in the drying agent has a significant vapor pressure.
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