Tuesday, September 27, 2011

An online gas lab simulation

Go to simulation.
You probably know the Ideal Gas Law well. An ideal gas is a hypothetical gas made of randomly moving particles that do not have a volume and do not interact with one another. Have your students ever asked questions such as "What about non-ideal gases? How good is the Ideal Gas Law for real gases?" I don't know about other people's experience, but I myself was intrigued by those questions when I learned the gas laws. Unfortunately, I couldn't go too deeply in trying to answer them because just thinking about the complexity of the motion and interaction quickly intimidated me.

Before computer simulation was widely accessible, you probably would have to pull out the Van der Waals Equation and pray that doing the math would do the trick.

Now, there is a good way to teach this. Using an online molecular dynamics simulation--made using the Molecular Workbench software, investigating non-ideal gases is a piece of cake. This simulation uses a pair of gas containers side by side and allows the user to explore how six variables affect the volume of  a gas: temperature, pressure, number of particles, particle mass, particle size, and particle attraction. It basically covers all the variables in the Van der Waals equation--without saying them explicitly. And there is a variable that is not included in the Van der Waals equation. The simulation reveals exactly why it is not there.

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