The intermolecular force between water molecules is hydrogen bonding, while the intermolecular force between ethanol molecules is van der Waals force. Hydrogen bonding is a stronger intermolecular force than van der Waals force.

Hydrogen bonding occurs when a hydrogen atom in a molecule is bonded to a highly electronegative atom, such as oxygen, nitrogen, or fluorine. The electronegative atom pulls the electrons in the bond toward itself, creating a partial positive charge on the hydrogen atom. This partial positive charge can then attract the partial negative charge on another electronegative atom, forming a hydrogen bond.

Van der Waals forces are weaker intermolecular forces that occur between all molecules. Van der Waals forces are caused by the temporary fluctuations in the electron clouds of molecules. These fluctuations create temporary dipoles, which can then attract each other.

Because hydrogen bonding is a stronger intermolecular force than van der Waals force, water molecules have a greater intermolecular force than ethanol molecules.