1. The problem statement, all variables and given/known data Explain the following features of ion-exchange resins in a home water softener. (a) Negatively charged sulfonate “sites” on resin molecules attract Ca2+ (aq) ions better than Na+ (aq) ions. (Consider the ion charges in your answer.) (b) Sodium ions from saturated NaCl(aq) replace calcium ions during regeneration. (Consider the concentration and collision theory in your answer.) 2. Relevant equations More concentration results in higher collision. 3. The attempt at a solution I think I've got a figured out; The negative charge attracts the positive charges. But since calcium has 2, it has a higher charge hence is attracts better than Na. I don't know what to do about b. Can I please get some direction?