And that means now we can talk about another gradient called the electrical gradient. Now, the electrical gradient is due to charge and not number. So the more charge there is here, the more our electrical gradient will play a role in dictating in which direction our molecule moves. And in fact, when the chemical gradient or the concentration gradient equals the electrical gradient, the rates that these molecules are moving inside is going to equal to the rates at which they're moving to the outside. And that's exactly what a rusting potential is. It's in the equilibrium state.