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Fractions of distillation .

  1. Feb 24, 2005 #1
    Fractions of distillation.....

    Some of the fractions which result from fractional distillation seem to share carbons of the same length - yet these form different fractions. Why?

    Eg - Petrol is carbon chain length 4 - 12, naptha is 7 - 14 and kerosine is 11 -15; why the overlap when they boil at very distinct temps. ie - petrol 40 - 100, naptha is 100 - 150 and kerosine is 150 - 250 degrees C.

    Thanks. :smile:
  2. jcsd
  3. Feb 24, 2005 #2


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    The simplest answer will be that boiling point depends not only on number of carbons, but also on the chain structure - whether it is straight or branched.

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  4. Feb 24, 2005 #3


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    "Distillation" --- evaporation of a MIXTURE. Do a few calculations of liquid and vapor compositions that are at equilibrium at the temperatures bounding the fractions you've listed.
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