Open the Experimental Apparatus in a New Window

In this experimental module you will be working with particles inside a balloon that is at constant volume (unless you pop it). You can control the temperature of the gas in the balloon by grabbing the thermometer with the mouse and adjusting the temperature (in Kelvins) up or down. Gauges read out the pressure (in weird units called Pascals) inside the balloon as well as the MPS (mean particle speed measured in meters/sec). A graph shows the distribution of particle speeds. The peak of that graph is approximately the same as the mean particle speed (mps).

Experimental Procedure

Lab Notebook Link

  1. Make and record pressure and MPS measurements at temperatures of 100, 200,400,800 and 1600K

  2. The balloon material is only rated to 150 pressure units. Given your data at what temperature to you think the balloon will burst. Test your prediction

  3. From your previous data, if you double the temperature does the MPS double? If not, by what factor does it increase (i.e. 10%, 20%, etc ...).

  4. If you now increase the temperature by a factor of 4, by what factor does the MPS increase?

  5. What do you think the proportional relation is between Temperature and MPS?

  6. Now qualitatively describe how the graph, which is showing the distribution of particle speeds, behaves as the temperature increases. (ignore the red vertical line on the graph).

  7. Given this behavior, how would you physically state that temperature manifests itself. That is, what does "temperature" really indicate?

  8. Clear the graphs and set the temperature to 400K to get one color curve and then set the temperature to 1600 K to another curve. Count the approximate number of boxes that are under the two curves. In doing this you are measuring the amount of area under these curves (in calculus this is called an integral). How many boxes are there for each temperature? (report them in the pressure column of the worksheet)

  9. Compare the two counts. Note that the Y-axis is the number of particles per cubic centimeter that are at some velocity. What might this comparison be telling you about the distribution of particle energies in this enclosed volume?

  10. Click to open a new balloon in a seperate window . Set the temperature to 1200K. Record the MPS and pressure. Suggest a reason that the values are different in this new ballon than in the previous one for this temperature (e.g. the step 1 values)