Why do linear molecules have a higher boiling point compared to branched molecules?

Linear molecules typically exhibit higher boiling points than their branched counterparts primarily due to their greater surface area, which leads to increased van der Waals attractions or London dispersion forces.

In linear molecules, the extended shape allows for more contact points between adjacent molecules, enhancing the overall intermolecular interactions. This increased surface contact means that when linear molecules are in close proximity, they can effectively interact with one another, which strengthens the forces that bind them together. Consequently, more energy is required to overcome these attractions during the transition from liquid to gas, resulting in a higher boiling point.

In contrast, branched molecules have a more compact structure, which limits the surface area available for intermolecular interactions. Consequently, the van der Waals forces in branched molecules are weaker, leading to lower boiling points. This fundamental difference in molecular arrangement and its effect on intermolecular attractions is why linear molecules generally have higher boiling points.