Question

Rank the following in order of increasing boiling point, based on polarity and intermolecular forces:

N2, PCl3, O2, NaNO3

Answer 1

N₂ and O₂ are non polar gases and will have only weak dispersion forces. PCl₃ is polar covalent, thus, shows dipole dipole interaction. NaNO₃ is ionic solid. Thus, NaNO₃ will be having highest boiling point followed by PCl_3. Since O₂ is larger in size than N₂, O₂ higher boiling point than N₂ as strength of dispersion forces depend on surface area. So increasing order of boiling point will be:

O₂ , N₂ , PCl₃ and NaNO₃