What happens to the boiling and melting points of carboxylic acids as their size increases?

As the size of carboxylic acids increases, their boiling and melting points increase primarily due to the greater molecular weight and the presence of strong intermolecular forces such as hydrogen bonding.

Carboxylic acids have -COOH groups that can form hydrogen bonds, leading to heightened attractions between the molecules. As the number of carbon atoms in the chain increases, the molecular size and surface area also increase, enhancing these intermolecular interactions. This results in more energy being required to overcome these forces when transitioning from solid to liquid (melting) or from liquid to gas (boiling), thus raising the melting and boiling points.

In summary, the trend for carboxylic acids is that with increasing size, both boiling and melting points rise due to stronger intermolecular forces caused by hydrogen bonding and increased molecular weight.