How do London dispersion forces relate to the boiling point of a compound?

Question

Isabella Acosta · Accepted Answer

More london dispersion forces increases the boiling point.

A good example of this would be the difference between saturated and unsaturated fatty acids:

Saturated fatty acids (like those found in butter/lard) stay solid at higher temperatures than unsaturated fats (like those found in olive oil).

This is because saturated fatty acids have a more linear structure, which gives them a greater surface area. Because of this, there are more london dispersion forces between the fatty acid-molecules as they can be "packed together" more tightly due to their straight structure, yielding a higher boiling point.

Conversely, unsaturated fatty acids have a bent structure and are more "bulky". The bend gives a smaller surface area and it is also harder to "pack together" than its respecitve saturated fatty acid.- Meaning it has a lower boiling point as there is less london dispersion force between the fatty acid molecules.

Carter Allen · Answer

undefined London dispersion forces, also known as van der Waals forces, are the weakest type of intermolecular force. They arise from temporary fluctuations in electron density within molecules, leading to temporary dipoles. Compounds with larger, more complex molecules tend to have stronger London dispersion forces due to increased surface area for electron interactions. Stronger London dispersion forces result in higher boiling points because more energy is required to overcome these intermolecular attractions and transition the substance from a liquid to a gas phase.