ChemActivity: Gas Properties with PhET
Instructions: Please read the directions that are provided with each model very carefully.
This simulation will provide you with many different ways to investigate the properties
of gases. You will be asked to select or move specific objects. This image will help you
to know the different objects: lid, pump, wall, heater/cooler, gas selector
LID
PUMP
WALL
HEATER/
COOLER
GAS
SELECTOR
There are also controls on the panel to the right. You will be directed to select or move
specific objects in order to observe certain gas behaviors so follow the instructions
carefully.
MODEL 1:
1. Use the toolbar on the right to keep the
temperature constant by clicking temperature:
Click the
tab.
Select the stopwatch. Grab the pump handle and pump it once. Click start on the
stopwatch. Wait about 30 seconds and record your observations.
2. Open the lid at the top by sliding it to the left all the way. Leave it open for about
a minute. (You can reset your stopwatch here). Record your observations. Close
lid before continuing.
3. Grab the handle on the wall and push the wall to the right so that it aligns under
the lid handle. Wait about 30 seconds and record your observations.
4. Use the pump to inject more gas into the chamber TWICE. Record your
observations.
5. What does the pump control in the experiment?
6. What does the handle on the wall control?
7. What does the lid do?
8. Explain what you observed in step 4. Why did this happen?
MODEL 2:
9. Click
to return to the original
settings. On the parameter list, select pressure
to keep it constant.
10. Pump in some gas. Record observations.
11. Why did this happen?
12. Can you use the handle on the wall to reset the volume to the original size?
13. What changed in this investigation?
14. Why did it change?
MODEL 3:
15. Click
to return to the original
settings. On the parameter list, select volume to
keep it constant.
16. Pump in some gas. Wait about 30 seconds then
record observations.
17. Pump in more gas and record your observations.
18. Why did this happen?
19. How can you change the pressure?
20. Is there a knob for the pressure like there is for volume and temperature?
21. Figure out a way to get the pressure to rise up to 2.5 atm. What did you do?
22. What could you do to get the pressure to return to below 1.00 atm?
23. Can you get it to exactly 1.00 atm?
24. Click
to return to the original settings again.
25. Pump in some gas (around 200 atoms).
26. Add heat using the heater at the bottom of the chamber and record your
observations.
27. Remove heat using the cooler at the bottom of the chamber
and record your observations.
28. Check the Energy histogram under tools and options.
29. Add heat again using the heater at the bottom of the
chamber and record your observations. Click
and start over from number 25 if the top blows off.
30. Now remove heat using the cooler at the bottom of the
chamber and record your observations.
31. Click
to return to the original settings again.
32. Add one pump of the heavy gas then switch to light gas using the gas selector
and add another pump.
33. Click more details button on the Energy histogram (particle statistics) and record
your observations.
34. Which gas has a higher average speed?
Analysis Questions:
1. What are the variables or characteristics that were investigated in this activity?
2. What happens to the pressure of a sample if more gas in injected? (assume
volume is constant)
3. What happens to the volume if pressure is held constant as the gas is injected?
4. Is it possible to increase the pressure without adding more gas? How can this be
done?
5. What happens to pressure if temperature is increased? (assume volume is
constant)
6. What affects the speed of the molecules?
Use this data table to help organize your observations. Record constant, increased or
decreased. Use arrows up and down for increase and decrease if you would like.
Question Molecular Pressure
Temperature Volume
Amount
Speed
mass
(heavy or
light)
1.
2.
3.
10.
16.
26.
27.
29.
30.
34.