The main intermolecular force between C3H7OH molecules is hydrogen bonding. Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom, such as oxygen or nitrogen, and is also attracted to another electronegative atom. In C3H7OH, the hydrogen atom of the hydroxyl group (OH) is bonded to oxygen, which is highly electronegative, and the hydrogen atom can be attracted to the oxygen atom of another C3H7OH molecule. This intermolecular attraction between C3H7OH molecules results in hydrogen bonding.

In addition to hydrogen bonding, there are also van der Waals forces acting between C3H7OH molecules. Van der Waals forces include dipole-dipole interactions, which occur between polar molecules, and London dispersion forces, which occur between all molecules, regardless of their polarity. The combination of hydrogen bonding and van der Waals forces contributes to the overall intermolecular interactions between C3H7OH molecules.