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Why does ethanal have a lower boiling point than ethanol?

Ethanol, due to the presence of its O-H bond, has the ability to form hydrogen bonds with other ethanol molecules. Hydrogen bonds form when there is the presence of a lone pair electrons (found on the oxygen), an oxygen, nitrogen or fluorine atom and a partially positive hydrogen atom. Ethanal is unable to form hydrogen bonds as there is no partially positive hydrogen atom in its structure. However, the molecule can form permanent dipole-permanent dipole bonds between each other due to the carbon being partially positive and the oxygen being partially negative in the C=O bond.Hydrogen bonds are stronger and require more energy to break than permanent dipole-permanent dipole bonds, therefore meaning more heat energy is required for the hydrogen bonds in ethanol to separate than the permanent dipole-permanent dipole bonds in ethanal to separate the individual molecules, thus giving ethanol a greater boiling point.

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