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Why does acetone have a lower boiling point than hexane? I thought that since hexane is non-polar then it should have weaker intermolecular forces and a lower boiling point, but it doesn't. Why?

For reference, the boiling point of acetone is roughly 56 °C while that of n-hexane is roughly 68 °C.

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  • $\begingroup$ Asphalt and parafin wax are just made of nonpolar molecules, too... $\endgroup$
    – Zhe
    Feb 24, 2018 at 3:12
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    $\begingroup$ Why a comparison between acetone and hexane? Why not between 2- or 3-pentanone (bp 101-102 $\ce{^{o}C}$, MW 86) and hexane (MW 86)? $\endgroup$
    – user55119
    Mar 26, 2018 at 14:53
  • $\begingroup$ The real surprise is that the smaller molecule acetone has nearly the same boiling point as hexane. $\endgroup$
    – matt_black
    Mar 27, 2018 at 14:49

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Hexane is a larger, longer-chain molecule so there are more London dispersion forces between n-hexane molecule which outweighs the dipole forces in acetone.

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