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Correlating density and melting point in alkenes

  1. Aug 19, 2016 #1
    Quoted data for cis and trans 1,2 dichloroethenes shows cis has higher density but lower melting point than trans. How can this be explained? Packing arguments are clearly unable to rationalise these observations. Other 1,2 disubstituted ethenes show similar pattern. Thank you.
     
  2. jcsd
  3. Aug 19, 2016 #2

    BvU

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    This homework ? What other property differs strongly ?
     
  4. Aug 19, 2016 #3
    Boiling points differ as expected - the more polar molecule (cis) is higher
     
  5. Aug 19, 2016 #4

    BvU

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    Yes, dipole moment is the key.
     
  6. Aug 19, 2016 #5
    Dipole moment explains boiling point but not the contrary melting point and density trend!
     
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