# Why does hydrochloric acid have a higher boiling point than diatomic fluorine?

Aug 11, 2017

Hydrogen chloride, is a room temperature gas. Its normal boiling point is $- 85$ ""^@C. Fluorine is a diatomic molecule, whose normal boiling point is $- 188$ ""^@C. Note that $H C l$ is water soluble to the tune of $10 - 11 \cdot m o l \cdot {L}^{-} 1$, and in this solution ionization occurs to give hydrochloric acid:
$H C l \left(g\right) \stackrel{{H}_{2} O}{\rightarrow} {H}_{3} {O}^{+} + C {l}^{-}$
Why the disparity in boiling point? Well hydrogen chloride is a larger, more diffuse, molecule, that has more opportunity for a dispersion forces. However, the principle intermolecular force that operates between hydrogen chloride molecules is hydrogen bonding; i.e. ""^(delta+)H-Cl^(delta-). The dipoles line up in the bulk phase, and this constitutes a potent intermolecular force......hence the respective boiling points.