Kinetic Molecular Theory

(modeling the behavior of gases)

Learning Outcomes and Objectives

After going through this learning module and reading the book about kinetic molecular theory, the student should have a basic understanding of the following concepts:

Your mission:

Use the gas simulator to determine the relationship between gas properties and gas kinetic energy and velocity.

Keep this simulator open while you work through the remainder of this module.

Do this: Click on the yellow gas cylinder (gas A) and then click on the barrel of the pump one time to add some more moles of gas to the container.

Notice this: In addition to the temperature, volume, and pressure readouts on the tank, in the upper right you will notice the "root mean square" or rms velocity of the gas particles along with the kinetic energy.  These are the average values for the sample in the simulator.  

Now Do this: Now change the volume, the pressure, the number of moles of gas, and temperature to see what effects the kinetic energy.   Note: it takes a moment for the simulation to "react" so change something and then wait to see what happens.  Don't just move knobs back and forth as there is a bit of lag time.

For the moment just use the yellow cylinder (gas A)

Question 1 - which property?

What properties affected the kinetic energy of the gas?

Do this: Click on the red cylinder (gas B) to activate the gas. Tap the pump two times to add some "red" gas particles to the cylinder. Now again you can play with the simulator and observed the changes in the rms velocities and average kinetic energies.

Question 2 - Comparing A and B

The two gases (red and yellow) in the simulator have _______ kinetic energies and _________ rms velocities.

  1. identical, different
  2. different, different
  3. different, identical
  4. identical, identical

You should now be working only with one gas (although you could mess around with two if you really want to).  

Get Temp in easy multiples of 10: Click on the "Cool" switch and cool as far down as possible. The temperature will only go down to 10 K. Now when you heat, you'll get "nice" divisible by 10 temperatures without the X.15...  

Do this: Now increase the temperature and see what happens to the kinetic energy to try to determine the relationship between the two.  

Observe: So try doubling temperature (easy if your in the double digits to start with) - what happens to the kinetic energy? Now triple the T. What is the KE?  You SHOULD see the relationship of kinetic energy and temperature. Do give the simulator time to react to your changes.

Question 3 - Temp relationship to KE

The kinetic energy of the gas in the simulation is related in what way to the absolute temperature?

  1. inversely proportional to the square root of temperature
  2. inversely proportional to temperature
  3. directly proportional to temperature
  4. independent of temperature

Again it is useful to note that experiments have shown that the average speed of gas particles is hundreds of m/s at room temperature.  If the particles in the simulator were actually moving at that speed, you wouldn’t be able to see them, so this simulator the gas particles are actually moving in slow motion (the correct speed is shown in the readout).

You should have found that the average kinetic energy is directly proportional to the temperature and is the same for all gases in a given sample.  The rms velocities however are different since different gases have different masses.