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Solubility of Non polar substances in water

  1. Oct 5, 2016 #1
    Water can dissolve O2 and CO2, both of which are non-polar....According to my understanding, water can only dissolve molecules which have polarity in their structure( like salt or sugar)....Oxygen gas is non-polar due to same atoms...I am not sure about CO2 but I think it is non-polar due to equal attraction of electrons...So why can water dissolve these two substances???
     
  2. jcsd
  3. Oct 5, 2016 #2

    Borek

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    Staff: Mentor

    To some extent everything dissolves in everything.

    CO2 is a bit different, as it not just dissolve.
     
  4. Oct 5, 2016 #3
    This.

    CO2 turns into carbonic acid in water
     
  5. Oct 6, 2016 #4
    Then it would not exactly be 'dissolving''...right??
     
  6. Oct 6, 2016 #5
    well it is considered as dissolution.
     
  7. Oct 8, 2016 #6
    The reaction of CO2 with water is reversible, so I suppose it's 'OK' to consider it as dissolution.
    In most cases however I suspect there should be no irreversible formation of covalent bonds, at most coordination (water solvates the molecules, so they separate and macroscopically the added substance 'disappears'), to be able to call it 'dissolution'. I'm sure physical chemists have a better definition; this is a messy organic chemist's point of view :wink:

    Examples of substances that will 'disappear' in water but are actually reacting (irreversibly, I think it's safe to say) rather than 'dissolving'.

    K
    NaH
    AlCl3
    SOCl2 (I guess some may even dissolve initially, but it won't hang around very long)
    ...
     
  8. Oct 8, 2016 #7

    James Pelezo

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    Gold Member

    CO2 is nonpolar b/c it is a linear molecule with diametrically opposing dipoles at 180o bond angle. => O=C=O and Oxygen (O2) is a triplet (dipole = 0) :O=O: that coordinates with Hydrogen in water ( ---:O=O:---H-O-H---:O=O:---). see also https://en.wikipedia.org/wiki/Triplet_oxygen
     
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