According to the data about the boiling point of different alkanes, we can observe that as the number of carbon atoms increases, the boiling point also increases no matter Alkanes or Alcohols. All first fifteen Alcohols have a higher boiling point than the first fifteen Alkanes when they contain the equal amount of Carbon atoms. For example, the Ethane C2H6 has the boiling of -89℃, whereas the alcohol that contains the same amount of carbon atoms - Ethanol C2H5OH has the boiling of 78.4℃.
The boiling point is the temperature at which liquids boil and turns to gases. The temperature represents how much energy is required for liquids to turn into gases. When liquids turn into gases, the intermolecular bonds between molecules break. Molecules which strongly interact or bond with each other through a variety of intermolecular forces(bonds) and can not move easily or rapidly. Therefore, molecules with strong intermolecular forces will have higher boiling points. This is a consequence of the increased kinetic energy needed to break the intermolecular bonds so that individual molecules may escape the liquid as gases.
The reason why alcohols have a higher boiling point than alkanes is because the intermolecular forces of alcohols are hydrogen bonds, whereas the alkanes with van der Waals forces.
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