Indicate the principal type of solute-solvent interaction in each of the following solutions and rank the solutions from weakest to strongest solute- solvent interaction: (a) KCl in water, (b) \(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) in benzene \(\left(\mathrm{C}_{6} \mathrm{H}_{6}\right),\) (c) methanol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right)\) in water.

The three solutions given are: (a) KCl in water (b) \(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) in benzene \(\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)\) (c) methanol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right)\) in water For (a), KCl is an ionic compound and water is a polar solvent. The principal interaction in this case is ion-dipole interaction. For (b), \(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) and benzene are nonpolar compounds, so the principal interaction in this case is London Dispersion Forces (LDFs). For (c), methanol and water are both polar molecules, and both can form hydrogen bonds. Thus, the principal interaction in this case is hydrogen bonding.

We have three types of interactions in the given solutions: 1. Ion-Dipole interaction (KCl in water) 2. London Dispersion Forces (LDFs) (\(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) in benzene) 3. Hydrogen Bonding (methanol in water) In general, hydrogen bonding is stronger than dipole-dipole interactions, and dipole-dipole interactions are stronger than London Dispersion Forces. Ion-dipole interactions are even stronger than hydrogen bonds. So, we can rank them as follows: Weakest interaction: \(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) in benzene (LDFs) Middle-strength interaction: methanol in water (hydrogen bonding) Strongest interaction: KCl in water (ion-dipole) Thus, the solutions are ranked from weakest to strongest solute-solvent interaction as: \(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) in benzene < methanol in water < KCl in water.