Explain why longer chain alkanes have a higher boiling point than shorter chains.

For the boiling point to be reached all of the intermolecular bonds must be broken. In an alkane the only two elements are hydrogen and carbon. The molecular structure of the alkane means that the intermolecular bond is an induced dipole-dipole/ van dar Waals force. The longer the chain, the more van dar Waals forces there is to break so more energy required therefore higher boiling point.