The boiling point of propanoic acid is higher than that of 1-butanol because: propanoic acid has a higher molecular weight than 1-butanol. propanoic acid is more soluble in water than 1-butanol. propanoic acid is a better hydrogen bond donor than 1-butanol. propanoic acid forms hydrogen bonded dimers and 1-butanol does not. 1-butanol forms hydrogen bonded dimers and propanoic acid does not.

propanoic acid forms hydrogen bonded dimers and 1-butanol does not.

Explanation:

Propanoic acids will have a higher boiling point because it forms dimers.

The two compounds have hydrogen bonds as their predominant intermolecular bonds. The intermolecular determines a lot about the physical properties of a substance such as it's viscosity, boiling point, melting point etc.

The two compounds have hydrogen bonds which are bonds that occur between between hydrogen and a more electronegative atom. The electronegative atoms are usually oxygen,nitrogen and fluorine.

In a compound of 1-butanol, we have just a single hydrogen bond between the hydrogen on one compound and the oxygen on the hydroxyl group of another one.

For, propanoic acids, dimerization occurs. Here, we have two hydrogen bonds. The alkanoic acid functional group furnishes the bond. This bond forms between the carbonyl group and hydrogen on a compound and the hydroxyl group and another hydrogen on the same compound.