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Homework Help: Sort these substances by boiling point

  1. Jan 24, 2009 #1

    they all are polar covalent
    except H_2 which is pure covalent
    how to sort them??
  2. jcsd
  3. Jan 25, 2009 #2
    Stronger bonds will have higher boiling points. Look in your chemistry book about the strengths of different types of bonds.
  4. Jan 26, 2009 #3
    it depends on the electro negativity value difference between two
    but here there are more then two ellements
    and more then one appearence
    of the same ellement

  5. Jan 28, 2009 #4
    Boiling point is a measure of the amount of thermal energy that has to be provided in order to overcome whatever intermolecular forces exist between the molecules of the material when it is in liquid form.

    Therefore, look at each of the species in question and work out which ones would likely have a notable number of (a) dipole-dipole attraction, (b) instantaneous-dipole/induced-dipole attractions, (c) hydrogen bonding, and which would only be likely to exhibit the weaker van der Waals type intermolecular forces.

    For example, you would expect H2O water to have a higher boiling point than CH3OH methanol because water has a higher dipole moment, and also a greater tendency for hydrogen bond formation (two hydrogen atoms with partial positive charge per molecule, as opposed to only one in methanol).

    If you take a look through the 5 compounds you have listed you should be able to rank them in this way.
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