Suppose you have a fused quartz tube with one closed end coiled into a spiral with a diameter of more than 10 m and you submerge it into a mixture of water and ethanol in a way that gets rid of all air then reposition it in such a way that it's partly submerged with the axis of the coil going nearly horizontally and slightly up in the direction from open end to closed end. Furthermore, suppose that the coil then starts moving and spinning along its length in the direction from open end to closed end and once the closed end passes the height where cavitation occurs, the closed end is cooled to recondense liquid there and after cavitation occurrs again on the next loop, liquid is condensed again in the same way? Is it true that if the concentration of water is above a critical concentration, it will become more concentrated after it cavitates and is recondensed because a smaller fraction of ethanol vapour will condense than water and if the concentration of water is below that amount, the water will become less concentrated after it cavitates and then is recondensed because a smaller fraction of water will evaporate than ethanol? Could really pure water be gotten in that way because fused quartz is extremely insoluble in water?

  • $\begingroup$ Units: 1 picture = 1,000 words ;) Also, do really mean a 10 meter diameter tube (or coil)? $\endgroup$ – airhuff Jan 20 '17 at 22:24

Since ethanol and the water-ethanol azetrope boil at a lower temperature than water, if you start with a lot of water with a smaller amount of ethanol then you can "distill" (however you do it...) all the ethanol out and be left with "pure" water.

But water and ethanol form an azeotrope which is 95.5% ethanol by weight and boils at 78.1 °C. For the water-ethanol azeotrope the wt. % ethanol in the liquid is the same as the wt % of ethanol in the vapor. Thus there is no way to exploit liquid to gas phase transition to enrich the ethanol more than that.

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  • $\begingroup$ How do you know a mixture of water and ethanol with 95.5% ethanol by weight can't be made into purer ethanol in that way? You haven't proven to me why that should be the case. Wouldn't very little water go from the liquid phase into the gas phase? $\endgroup$ – Timothy Jan 21 '17 at 2:48
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    $\begingroup$ Proof? LOL - Let's start with 1+1=2... // See phase diagram for water-ethanol here, not exact scale, but gives the idea. chemguide.co.uk/physical/phaseeqia/bpcompn1.gif // webpage chemguide.co.uk/physical/phaseeqia/nonideal.html $\endgroup$ – MaxW Jan 21 '17 at 3:27

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