Molecules of hydrogen chloride, HCl, and molecules of fluorine, F2, contain the same number of electrons. Hydrogen chloride boils at –85 °C and fluorine boils at –188 °C. Explain why there is a difference in the boiling points of HCl and F2.

F2 has temporary dipole-dipole interactions known as van der Waals’ forces. Whilst HCl has permanent dipole-dipole interactions. The intermolecular forces in HCl are stronger than that in F2 (permanent dipoles are stronger than induced dipoles). More energy is required to break stronger intermolecular forces, therefore, HCl has a higher boiling point