Question

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

Answer 1

Well, consider the intermolecular forces that operate within each substance......

Explanation:

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 `HCl` is water soluble to the tune of `10-11*mol*L^-1`, and in this solution ionization occurs to give hydrochloric acid:

`HCl(g) stackrel(H_2O)rarrH_3O^+ + Cl^-`

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.