The following is the electrostatic potential plot along the z-axis in a liquid-liquid biphasic system (a ionic-liquid vs water).
There are some negatively-charged ions in the positive side of z (z > 0). The above curves are the total of all potentials (including the ions itself) in two systems with different parameters. I would like to know how the negatively-charged ions behave in each.
I myself think of the curve as a path on which the ions like balls must roll up/down under the force of electrical field. So, they won't move much in the flat areas. Is it correct? According to this analogy, can we say moving a charged bar in the orange curve is easier because it is more smooth?