Why is CH2Cl2 polar?

Discussion in 'DAT Discussions' started by vindicate, May 30, 2010.

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  1. vindicate

    vindicate

    105
    1
    Sep 20, 2009
    Hi guys,

    I was hoping you could help me out on this.

    ''''''''' H
    '''''''''''..
    '''''Cl-C-Cl
    '''''''''''..
    '''''''''''H


    the above is what i pictured when i saw CH2Cl2.
    destroyer says its polar because they pictured it like the diagram below.
    Can anyone tell me why CH2Cl2 has the below conformation over the one above?


    ''''''''''H
    ''''''''''..
    '''''H-C-Cl
    ''''''''''..
    ''''''''''Cl
     
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  3. 476515678234896

    476515678234896 Banned Banned 7+ Year Member

    920
    1
    May 7, 2010
    i have no idea what you drew but the chlorine atoms are more electronegative than carbon (carbon is more electropositive than cl) and makes 2 delta negative charges in the cl's direction. The net charge is out between the chlorine making it polar.
     
  4. PeachyPhd

    PeachyPhd 2+ Year Member

    375
    0
    Mar 10, 2010
    Alabama
    Army
    Don't forget that these are three-dimentional structures. If you build a model, you might answer your own question.
     
  5. Baylor2011

    Baylor2011 DDS Apprentice 2+ Year Member

    451
    0
    Sep 10, 2009
    Texas
    Draw it with molecular geometry...which in this case is a tetrahedral.

    No matter which way you arrange the atoms, the 2 chlorine dipoles never cancel each other out.
     
  6. vindicate

    vindicate

    105
    1
    Sep 20, 2009
    thanks. makes sense.
     
  7. Imanm

    Imanm 2+ Year Member

    95
    0
    May 20, 2010
    this is very easy to get confused over but if you think about it it actually is very simple.
    if you were to see an atom, it would look like a sphere. as you know the internal angle of a circle is 360 degrees. now if you have an atom connected to four other atomes, keeping in mind that the electron clouds within these bonds repel each other and want to stay as far away as possible from each other, youd have to devide 360 by 4 which comes out to 90 if the atom was a flat circle. however since atoms are spherical and 3D they are able to push these bonds to about 109 degrees away. now keeping in mind that the two C-Cl bonds are 109 degrees away from each other and also more polar than the C-H bonds you can clearlly see that the molecule is polar. compare this with CO2 which has two C=O bonds 180 degrees apart. because of the fact that they are 180 degrees apart they are exactly in opposite directions from each other therefore canceling out eachother's the polarity.
     
  8. sfoksn

    sfoksn 7+ Year Member

    761
    1
    Sep 3, 2006
    You drew the exact same molecule twice :confused:
     
  9. tommyngu

    tommyngu 5+ Year Member

    71
    13
    May 29, 2010
    Southern California
    yup, those two drawings represent the same thing. draw or build a 3d model of it. no matter where you put the 2 Cl atoms, it will be the same molecule.
     
  10. INH

    INH 2+ Year Member

    10
    0
    Aug 4, 2013
    just reemphasizing that CH2Cl2 is tetrahedral and one half of the molecule with always have a more electronegative charge than the other half depending on how the chlorines/hydrogens are bonded to the central carbon (109.5 degree bonding angles).this unequal distribution of poles makes CH2Cl2 polar
     

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