UTF-8Simulation Challenge -- Purification by EffusionEffusion as a means of separating gases of different molecular mass
For a definition of effusion see: http://en.wikipedia.org/wiki/Effusion
Simulation by: Enter your name here
Now use what you have to learned to set up a simulation to see study how effusion of gas molecules from a small hole can be used separate the gases according to mass.
This method is used to separate Uranium-235 from Uranium-238 by "gaseous diffusion" see: http://en.wikipedia.org/wiki/Gaseous_diffusion to make nuclear fuel and bombs.
1. Add two different types of gas molecules to the small space on the left of the barrier.
2. Make the molecules the same size (no more than 1.5 Å radius).
3. Make their masses very different -- use 4 and 64 g/mol
4. Make the intermolecular attractions very small for both types of molecules: set epsilon = 0.001
5. Put the same number of molecules of each type together in the small space on the left -- put at least 20 molecules of each type.
6. Set the heat bath to a temperature of 1000 K (you can change this later to find what works best).
7. Allow the simulation to run for about 100 pico-seconds to equilibrate.
8. Then open a small hole in the barrier for Effusion to occur - just big enough for one particle to pass at a time.
Note: You can play with the size of the whole and the thickness of the barrier to get the best separation in the shortest time.
9. Run the simulation again to see what happens. Run the simulation until 50% the molecules of the faster type have escaped to the right side of the barrier
by effusing through the hole. Stop the simulation and count the number of the heavier molecules that also escaped.
Assuming you started with equal number of particles estimate the purification ratio this way:
Purification ratio = (Number of escaped fast particles )/(Number of escaped fast + number of escaped slow particles)
The higher the Purification Ratio (closer to 1) the better the separation. Report your purification ratio here:
Purification ratio = ______.
10. Now try to improve the apparatus to achieve a better separation -- i.e. purification ratio.
11. Figure out a way to trap the molecules at the other end.
12. Save your simulation with the file name "your_Name_Purification_by_Effusion" and uploaded it on the MW website so we can
evaluate them. Enter your new Purification ratio for your improved apparatus:
Purification ratio for improved simulation = ______.
Explain here how you modified the apparatus to achieve a better separation of the two types of molecules
and to trap one type of molecule on the other end of the apparatus and why you did it this way.
Discuss the results -- did it work? This is an opportunity for you to demonstrate and develop your creativity!
Here is a space to type your discussion. Also copy your discussion and provide a link for your simulation on Blackboard:
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