Why does butane have a higher boiling point than ethane?

GCSE answer: Butane is a larger molecule than ethane meaning that the intermolecular forces between its molecules are stronger. In order for a compound to boil these intermolecular forces need to be overcome. Stronger intermolecular forces take more energy to overcome therefore the stronger the intermolecular forces, the higher the boiling point. This means that butane will have a higher boiling point than ethane. More advanced answer: Intermolecular forces in non-polar molecules such as these are caused by instantaneous and induced dipole interactions. The larger size of the butane molecule means that it has a larger electron cloud which can become polarised so the instantaneous or induced dipole will be larger, creating stronger intermolecular interactions therefore raising the boiling point.