In the real system we would have to take into account the interactions between ions and the structure of the solvent in response to all the ions. But for the purposes of class, we will only worry about the calculations which involve a simpler system that is similar to the reference system.
In the real system we would have to take into account the interactions between ions and the structure of the solvent in response to all the ions. But for the purposes of class, we will only worry about the calculations which involve a simpler system that is similar to the reference system.