Problem 13.16

Indicate the principal type of solute-solvent interaction in each of the following solutions, and rank the solutions form weakest to strongest solvent-solute interaction.

(a)KCl in water

KCl is ionic; the main solvent-solute interaction here is the ion-dipole interaction (remember that ionic compounds exist as ions in solution.)

(b)CH₂Cl₂ in benzene C₆H₆

CH₂Cl₂ is polar (draw the Lewis structure - it has the general formula AB₂C₂, so even though it is tetrahedral, it is polar.) Benzene is nonpolar, so the only interaction possible is the London dispersion interaction.

(c)methanol, CH₃OH, in water

Draw the Lewis structure for methanol: There is a hydrogen bonding interaction between the hydrogen attached to the oxygen in methanol and the oxygen atom of water.

In order of increasing magnitude, we have dispersion < H bonding < ion-dipole.