by horse Comment Closed

LARN 108 C27D4

Bring in one empty aluminum soda, tea, or juice can to use in your next laboratory investigation.  If you have extra empty aluminum cans and wish to donate them for use by other students, please feel free bring them in.

Start the following in class:

With your laboratory notebook open for note taking, click on the online states of matter simulation link provided:  States of Matter Basics.   The simulation can be run in your browser online but if it loads too slowly, one can download the simulation and check whether it runs better directly on your device. Click on the right pointing triangle displayed in the center of the simulation screen to launch the HTML5 app.

  •  Your Goal: For each set of variables specified below, take a couple of minutes to play around and observe.  Record what happens when each of the variables in the simulation changes while the other variables stay the same.  As a result of finishing this simulation, you should be able to describe what corresponding change, if any, takes place in the other variable(s) when one variable is forced to increase or decrease in value.
  • As you perform the laboratory simulation, record the step letter/number designator given below to the left of your vertical red marginal line and record your observation(s) for that step to the right of the line.

A. Select the States of matter screen.

  • A home icon, an icon for the states of matters screen, and an icon for the changes in phase and phase diagram screen now display at the bottom of the simulation window.
  • Click on the peach colored Solid phase selection bar underneath the Atoms & Molecules graphic selection menu and turn it a light violet color.
  • You will choose each type of molecule displayed in the legend in the upper right corner of the display.
      1.  First the neon monatomic molecules (cyan in color).
      2.  Then the argon molecules (larger monatomic molecules than neon’s) (a light stippled red in color).
      3. Then the oxygen diatomic molecules (red in color).
      4. Then the water triatomic molecules (red and white in color).
      1. For each particular type of molecule, adjust the Heat/Cool lever to cool the molecules (absorb energy) until the absolute temperature is near 0 kelvin and
        • Record the temperatures at which phase changes take place.
        • Record the motions you observe in the simulation: increases or decreases in translational, rotational, or vibrational motions.
      2. For each particular type of molecule, adjust the Heat/Cool lever to add energy until the absolute temperature is near 1 000 K.
        • Record the temperatures at which phase changes take place.
        • Record the motions you observe in the simulation: increases or decreases in translational, rotational, or vibrational motions?
      3. Think about what you have observed and write down a paragraph summarizing what you have learned.
      4. At the same temperature, do the molecules in a sample of the same substance all travel at the same speed?  In a paragraph explain why this is so.

Share what you have learned with a learning partner when you get to class.

Recommended for those who have time left in their 45 minute study period, but not required of all: 

B.  Select the Phase Changes screen.

Start with a chunk of solid composed of many molecules or start by pumping in at least 15 molecules with the bicycle pump,

  1. Choose a specific type of molecule, neon monatomic molecules.
  2. Click on the + Phase Diagram button.  Note that as temperature increases, the red dot on the phase change diagram traces out a sublimation curve first and then a boiling point curve.  [The critical temperature of a particular gas is the specific temperature above which no amount of pressure can liquefy the gas.] If the red dot moves above the critical temperature/critical point, the simulation needs to be reset before it will move again.
  3. Adjust the Heat/Cool lever to cool the molecules (absorb energy) until the absolute temperature is near 298 kelvin.
    1. Record the initial temperature and the pressure as shown on the pressure gauge in units of standard atmospheres.
    2. Push down on the container lid with your simulated forefinger and record your estimate of the average absolute temperature and pressure.  If the pressure inside the container reaches 200 atm, the container lid blows off and molecules escape from the container.  If that happens, click on the Return Lid button that appears, and pump in as many extra molecules as you want, or click on the reset button in the lower right corner of the display and continue to simulate experiments.
    3. Check position of the red dot on the Phase Diagram. [If the red dot moves above the critical temperature/critical point, the simulation needs to be reset before it will move again.]
  4.  Adjust the Heat/Cool lever to add energy until the absolute temperature is near 1 000 K.
    1. Record the initial temperature and the pressure as shown on the pressure gauge in units of standard atmospheres.
    2. Push down on the container lid with your simulated forefinger and record your estimate of the average absolute temperature and pressure.  If the pressure inside the container reaches 200 atm, the container lid blows off and molecules escape from the container.  If that happens, click on the Return Lid button that appears, and pump in as many extra molecules as you want, or click on the reset button in the lower right corner of the display and continue to simulate experiments.
    3. Check position of the red dot on the Phase Diagram. [If the red dot moves above the critical temperature/critical point, the simulation needs to be reset before it will move again.]

e. Adjust the Heat/Cool lever to add energy until the absolute temperature is near 0 K.

    1. Record the initial temperature and the pressure as shown on the pressure gauge in units of standard atmospheres.
    2. Push down on the container lid with your simulated forefinger and record your estimate of the average absolute temperature and pressure.
    3. Record the position of the red dot a sketch of the Phase Diagram in your laboratory notebook. [If the red dot moves above the critical temperature/critical point, the simulation needs to be reset before it will move again.]

2. a.-e., Repeat your investigations with the argon monatomic molecules and record any differences that you observe.

3. a.-e., Repeat your investigations with the oxygen diatomic molecules and record any differences that you observe.

4.a.-e.  Repeat your  investigations with the water triatomic molecules and record any differences that you observe.

5. Think about what you have observed.  What similarities in the behavior of the gases do you notice?  Write a paragraph summarizing what you have learned.

6. How can a substance be at a uniform temperature and yet be in different phases?  Write  a full paragraph explanation to answer this question.

  Share what you have learned with a learning partner when you get to class.