Question

Which of the substances have polar interactions (dipole–dipole forces) between molecules?

a) O₂ (oxygen gas).
b) N₂ (nitrogen gas).
c) H₂ (hydrogen gas).
d) HCl (hydrochloric acid).

Answer 1

HCl (hydrochloric acid) exhibits polar interactions or dipole-dipole forces due to the difference in electronegativity between hydrogen and chlorine. In contrast, O₂, N₂, and H₂ are nonpolar molecules with no permanent dipole moments, thus they only exhibit dispersion forces.

Step-by-step explanation:

Among the substances given, HCl (hydrochloric acid) has polar interactions, namely dipole-dipole forces. In the HCl molecule, there is a partially positive hydrogen atom and a partially negative chlorine atom due to the difference in electronegativity between the two atoms.

As a result, in a collection of HCl molecules, these molecules will align themselves such that the oppositely charged regions of neighboring molecules are near each other, which is characteristic of dipole-dipole interactions.

Substances a) O₂, b) N₂, and c) H₂ are all diatomic molecules made up of the same element, which means they are nonpolar and do not have permanent dipole moments.

Therefore, they do not exhibit dipole-dipole forces but instead exhibit dispersion forces, which are the weakest type of intermolecular force.