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Butane and Hexane - Why Different Boiling Points

Butane, CH3CH2CH2CH3, has a boiling point of 0.4ºC, and hexane, CH3CH2CH2CH2CH2CH3, has a boiling point of 69ºC. Both are nonpolar molecules. Explain the large difference in the boiling points of these two substances.

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The large difference in the boiling points of butane and hexane can be attributed to intermolecular attractions. Hexane is a large molecule (Molecular weight = 86) and has more electrons and nuclei that create stronger van der Waals attractive forces, not so easy to break. Butane is a smaller molecule (Molecular weight = 58) and has comparitively weaker van der Waals forces.

Due to this reason, hexane has a higher boiling point while butane has a lower boiling point.