(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.
Doug Chapman firstname.lastname@example.org 7/2/08