This simulation measures the amount of sodium ions that come into and diffuse out of a cell membrane. Each of the stocks represents the sodium inside and outside the membrane. Each also have an initial value that can be manipulated. The rate at which they reach equilibrium can be measured my multiplying a time by the amount of ions in each respective area of the cytoplasm. By looking at the amount of ions on each side of the cytoplasm, we are able to see the equilibrium quantity of ions. The intersection of the graphs shows the equilibrium quantity as both curves increase and decrease respectively.