As the size of a hydrocarbon molecule increases, what happens to its boiling point?

As the size of a hydrocarbon molecule increases, its boiling point tends to increase. This is primarily due to the fact that larger hydrocarbons have more atoms, which leads to a greater number of electrons. An increase in the number of electrons results in stronger van der Waals forces (also known as London dispersion forces) between the molecules.

These intermolecular forces need to be overcome for the substance to change from a liquid to a gas, which occurs at the boiling point. Therefore, as hydrocarbons grow larger and the strength of these intermolecular forces increases, more energy is required to break them apart during the phase change from liquid to gas. Consequently, the boiling point rises with the larger size of the hydrocarbon molecules.