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Old 21-04-2012, 08:37 AM
PobodY PobodY is offline
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Join Date: Apr 2012
Location: Crewe, UK
Posts: 8
Default Re: Water + ethanol/isopropyl

Again, sorry to re-animate dead threads...

Is the issue with these mixtures to do with the formation of azeotropes? - I was also thinking about other alcohols that could be mixed with water; they are, after all, pretty similar (one alcohol functional group, and slightly different chains on the end).
However, one thing I noticed is that methanol has no azeotrope with water (in that if you mix them you don't get a "super solution" with properties different from either of the constituents), but ethanol, n/iso-propanol, x-butanol, etc all do.

So a methanol/water mixture can be separated back into methanol and water; each with its own boiling point (and therefore, I assume, heat capacity). However when you put isopropanol or ethanol into the mix you get an azeotrope with a much lower boiling point.

Similarly (because I've seen it in another thread) methanol and nitromethane form an azeotrope at 9% nitromethate; that will boil at a slightly lower temperature than methanol alone (and a lot lower than nitromethane alone).

This got me thinking; is there a way to make this work to our advantage? Perhaps a negative ternary azeotrope which is better than all the constituents...

...but it also occurs to me that I might be thinking too much, and that I should just stick to what it known to work.
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