The Dance:  A Culminating Assessment Activity

Now that you have explored molecular motion from both within and between molecules, let's examine some questions that bring all the aspects we have explored together.

1.    Let's examine the internal rotation along the oxygen-oxygen bond in di-t-butyl peroxide, which is shown below. 

The video to the left is the using the wooden ball-and-stick model, while the one on the right is a computer animation using Spartan '02 (large file, slow loading).  Compare and contract the two models.

2.   Examine the hydrocarbon molecule given below, which is in its lowest energy state, (most stable, by AM1 minimization using Spartan '02).

Now examine the molecular dynamics of this molecule by running the Java applet - click here.  Allow the applet to run for a while and view it.  Describe the types of motion shown in this simulation.

3.    Examine the structure of the three molecules in their lowest energy states given below.  The left most is biphenyl, the other two are disubstituted biphenyls- dichloro (middle) and dimethyl (right).  A molecular model kit is available if needed!

For the relative energies as a function of rotation angle (torsion angle) for the carbon-to-carbon bond connecting the two rings, which molecule goes with which curve?

A _____________        B ______________        C _______________

4.    Water has three modes of vibration and two of these modes have very similar wavenumbers.  The IR spectrum is active in Chime, right click for the menu.  Identify the two peaks on the IR spectrum of water given below.  Give the wavenumbers and mode.

Source of IR spectrum:

5.    You have two one liter containers- one with helium gas at STP and the other with carbon dioxide gas at STP.  What would be the same for both containers?  What would be different for the two containers?  Venn diagram format for the answer would be nice!

Return to The Dance of the Molecules webpage.