Question

Is it possible to obtain pure (200-proof) ethanol using fractional distillation from a fermentation mixture that contains equal amounts of water and ethanol? Explain your answer.

I know that some water will still remain i would just like to know why some water vapor will be present at the low bp of ethanol.

Answer 1

The reason is that there is a vapor pressure present in water in any temp, even at room temp.

http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/watvap.html