Water and Intermolecular Forces with AtomSmith

For this exercise, you will need access to AtomSmith. 

Pingry has a site license which allows our students to use the program.  If you are in my class,

AtomSmith is a cool molecule simulator.

you should have received an email from Bitwixt software explaining how to download and install the software.  If you did not receive the email or lost it, let me know and I will ask them to send you one. 

If you are not a Pingry student, you may be able to get a trial version from Bitwixt by contacting them.  I know they have a student licence for about $50.

The tutorial below will explain how to use AtomSmith.

Launch the program and go to simulation --> open the gas lab.

Put about 16 water molecules in the box and start the simulation.  Vary the temperature so that you see water in all three states.  

    You should be able to explain how molecular motion differs in solids, liquids and gases.  

    You should be able to identify the intermolecular forces at work.

Methane has about the same molar mass (16 amu) as water (18 amu).  Again, vary the temperature so you see methane in all three states.  

• Are the melting and boiling points higher or lower than water?  
• What intermolecular forces are at work? 
• Explain the difference in boiling and melting points with respect to the intermolecular forces.

Add water, ethane and ethanol to the box (about 5 molecules of each).  Lower the temperature and let the molecules come together, then raise the temperature.  

• Which molecules interact the most?
• Explain why in terms of the intermolecular forces involved.

Add water and chloride ions.  Describe and explain the interactions.
Add water and sodium ions.  How is this similar and how is it different from the chloride?

Use your imagination and explore any other combinations you'd like from the list available.

 Go to the Library of 3-D Molecular Structures at NYU.  Download a fatty acid molecule (you should be able to figure out which ones these are.  Go to file --> open model.  Navigate to the file you downloaded.  Go to simulation-->open the gas lab.  Add a couple of water molecules and a couple of hexanes.

• Describe the interactions of water and hexane with the fatty acid molecule.
• Explain why these molecules interact this way in terms of the intermolecular forces involved.
• What is the significance of this to life?

  Play with other molecules and see how they interact.  Post comments on anything you find interesting.