Solubility and Miscibility Question

weanprednisone

Full Member
5+ Year Member
Jun 6, 2015
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  1. Medical Student
    Question: What is the reason why methylene chloride is miscible in Hexane?

    My reasoning is #2 below:
    Methylene Chloride is a polar molecule due to the 2 dipole-dipole interactions bonds (C-Cl) -|->
    Hexane is a nonpolar molecule due to the dispersion/london/vdw forces.

    1. Peers say they are miscible because methylene chloride is actually a non-polar molecule. So like dissolves like, nonpolar would mix with nonpolar molecules.
    But I am for sure methylene chloride is polar.....

    2. Is it because methylene chloride and hexane have a similar IMF attraction? Just the CH2 in methylene chloride is attracted to the dispersion forces in hexane? Does the 2 Cl not play any role in the reasoning?

    I want a confirmation, because I often just look at the nonpolarity & polarity, and sometimes forget about the IMF behind it (H-bonding, dispersion, dipole-dipole), even though sometimes they are related.

    That being said,
    1. two molecules that can H-bond will always be miscible/soluble (if with under 4 carbons)
    2. two molecules that has dispersion forces, will always be miscible/soluble.
    3. what will happen if the two molecules have dipole-dipole interactions, are the at all attracted?
    misciblility and solubility is interchangeable right?
     

    m3camp

    New Member
    Jan 29, 2016
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    1. Pre-Medical
      CH2Cl2 is in fact POLAR because it has a net dipole moment of 1.6. This is because the molecule is tetrahedral therefore 109.5 bond angles so the Cl atoms do not cancel out. They contribute to a net dipole.

      Hexane is obviously a nonpolar alkane.

      However, LDF forces accumulate as the # carbons increases. Hexane has more LDF than Methane for example. That being said, the aggregate LDF of Hexane is enough to make CH2Cl2 partially soluble in it. Likewise CH2Cl2 is miscible in Benzene (even though benzene is nonpolar).
       
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