The following substances dissolve when added to water. Classify the substances according to the strongest solute-solvent interaction that will occur between the given substances and water during dissolution.

1. ion-ion forces

2. dipole dipole forces

3. ion dipole forces

4. london dispersion forces

A. HF

B. CH3OH

C. CaCl2

D. FeBr3

Answer: HF-dipole - dipole interaction

CH3OH - dipole-dipole interaction

CaCl2 - ion-ion interaction

Explanation:

Both CH3OH and HF possess permanent dipoles which interact with water leading to the dissolution of the above named substances. Remember that water also possesses a permanent dipole. Which can interact with the dipoles on other polar molecules. CaCl2 is purely ionic and interacts with water via ion-dipole mechanism.