Ionic liquids (ILs) are salts that are in the liquid state. At a given temperature, ILs have lower vapor pressures than molecular compounds in the liquid state because the forces of attraction between oppositely charged ions are much stronger than intermolecular forces. Thus, ILs tend to be much less volatile and less flammable than many other liquids. ILs are of interest because of their potential role as “safer” and “greener” solvents. Two examples of ionic liquids are 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF₄], and 1-allyl-3-methylimidazolium chloride, [Amim]Cl, both of which consist of a relatively large organic cation and an inorganic anion.

(a) Look up and then draw the structures of the ions making up these two ILs.

(b) Find the melting points for these two ILs and for NaCl.

(c) Explain why the melting points of these two ILs are much lower than that of NaCl.