Molecules mixing

When the simulation starts, two different types of molecules start in opposite halves of a container. The molecules start moving in random directions, and they collide with each other and the walls of the container elastically so that the total kinetic energy of the system remains constant. As the molecules move and collide, they will mix.
This simulation shows ideal mixing.

Learning outcomes

• Understand that the entropy of a mixture is higher than the entropy of its separate components.
• Appreciate that mixing tends to occur spontaneously.
• Begin to understand the concept of thermodynamic equilibrium.
• Describe changes in Gibbs free energy as a spontaneous process proceeds.

Instructions

The 400 molecules (200 of each colour) will start moving as soon as the page loads.

Watch the process of them mixing due to their random motion. You can reset the simulation using the button towards the bottom of the page.

The molecules may occasionally stick together, but should break apart again.

Questions

1. Is this an open, closed or isolated system?
2. What happens to the entropy of the system as the mixing occurs?
3. What is the enthalpy of mixing in this system?
4. Does the temperature of the system change as mixing occurs?
5. Will ΔG for this mixing be positive, negative or zero?
6. How will ΔG change as the mixing proceeds?
7. How would ΔG change if the temperature was changed?