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Homework Help: Hydrogen Bonding

  1. Sep 6, 2005 #1
    Hi, i have more of a chemistry than a physics question. I am conducting an experiment to seperate ethanol from water via fractional distillation, however through calculations i have found that some of the ethanol remains bonded to the water due to the strong hydrogen bonds. Is there any other way of weakening hydrogen bonds other than just simply heating the solution?
  2. jcsd
  3. Sep 6, 2005 #2


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    You can not get ethanol more concentrated than 96% by fractional distillation. "Absolute" ethanol is obtained by distillation, if some amount of benzene is added. (I do not know the details, look after. ) Or you can dry the ethanol by pieces of freshly cut potassium metal.

  4. Sep 6, 2005 #3
    hhmmm, ok thanks, this lead me to another question. you can increase the boiling point of water by adding salt to it, is there any other compound that could be added to water to increase the boiling point of water higher than salt does?

    my idea is that if you can increase water's boiling point far enough you can increase the water/ethanol solution tempurature to say about 92 degrees celsius, which will boil almost all of the ethanol (with a boiling point of 87.3 degrees celsius) and not boil any water with it, because sometimes water boils at less than 100 degrees.
  5. Sep 6, 2005 #4
    Depends what you're after but if you oxidise the ethonol to ethanal you reduce it's boiling point to 20 odd dergees C. But if you want to keep it as ethanol then the benzene method is the best, but even then it will absorb moisture from the atmosphere until it reaches 96% ethanol.
  6. Sep 6, 2005 #5
    hey does salt dissovle or react with ethanol ?
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