This simulation shows the behavior of water and solute in an idealized, simple solution. Initially only 150 water molecules are present, and they are exhibiting Brownian motion. Use the pull-down menu at the lower right to increase (or decrease) the number of solute molecules in solution. Clicking on the large compartment itself resets the simulation to its starting condtion.

Each additional solute associates with several water molecules: in this simulation, 3. When no solute is present, 150 water molecules are free. When 10 solute atoms are added, and the initial volume maintained at 150 particles, only 140 water molecules are present and 110 of these are free. What do you think would happen to the solution, if the solute amount were increased to 30? Try it and see!

Let's now consider a more complex system and the process of osmosis. Imagine what would happen if two compartment of equal size and equal numbers of water and solute molecules were placed in contact with each other, but only water could diffuse between them. Go to the next page to examine this situation.