Gases Simulation

Gas Properties Simulation Summary Activity
Name ___________________________
Go to: http://phet.colorado.edu/en/simulation/gas-properties
Run the java application. Set up the simulation according to the instructions and answer the questions.
Kinetic Energy and Speed: Compare the kinetic energy and average speed at two different
temperatures and record your results in the table below.
Directions:
1. Set volume as a constant parameter
2. Enter 100 heavy species of the gas into the chamber
3. Wait for the gas particles and numerical values to equalize.
4. Record the temperature (T1)
5. Check “species information” and record the average speed
6. Change the number of heavy species to 0 and enter 100 light species of gas into
the chamber. Record the average speed for the light species.
7. Use the heat control to add or remove heat and change the temperature of the
system. Record this as your T2 and repeat steps 2-6.
8. Enter 100 heavy and 100 light species into the chamber at the T2 temperature to
examine a mixture of particles.
“Heavy” Particles Only
“Light” Particles Only
Heavy + Light Mix.
Average Speed for T1
T1 = __________K
Average Speed for T2
T2 = __________K
1. Compare the average speed for the heavy vs. light particles at the same temperature. Are these the
same or different? What does this tell you about the kinetic energy of the particles? Whose gas law
describes this relationship?
2. Compare the average speed for the heavy vs. light particles at different temperatures. Are these the
same or different?
3. Compare the average speed of the mixture to those of the heavy-only and light-only gases at the
same temperature. Are these the same or different?
4. Summarize your observations about the relationships between molecular mass (heavy vs. light),
kinetic energy, particle speed, and temperature.
Kinetic Molecular Theory (KMT) of Gases
Our fundamental understanding of “ideal” gases makes the following 4 assumptions.
Play with the simulation and describe/draw how each of these assumptions is represented in the
simulation.
Assumption of KMT
1. Gas particles are separated by
relatively large distances.
2. Gas molecules are constantly in
random motion and undergo elastic
collisions (like billiard balls) with
each other and the walls of the
container.
3. Gas molecules are not attracted or
repulsed by each other.
4. The average kinetic energy of gas
molecules in a sample is proportional
to temperature (in K).
Representation in Simulation
Relationships Between Gas Variables
Using the following table, hold one of the variables constant and explore the relationship between the
other 2 variables. Draw/describe what happens when you manipulate the 2 variables. Determine what
type of a relationship is present (direct or inverse) and whose gas law describes that relationship.
Constant
Parameters
Variables
to be
manipulated
temperature
pressure,
volume
volume
pressure,
temperature
pressure
volume,
temperature
pressure
volume,
number of
gas particles
Drawing/Description
Relationship
(Direct or
Inverse)
Name of
Gas Law
Pressure and Mixtures of Gases
The atmosphere is composed of many gases in different ratios, and all of them contribute to the total
atmospheric pressure. Use the simulation to explore this relationship by testing combinations of heavy
and light gases.
For each Test #, record your measurement and the make the prediction before moving on to the
next row of the table. You can hit “reset” in between each one.
Test
#
1
Pressure
Measurement
100 Light particles =
Pressure Prediction
(greater than, equal to, less than, twice as much, half as much, etc)
Pressure for 100 Heavy Particles will be __________________ the
pressure from Test #1.
2
100 Heavy particles =
Pressure for 200 Heavy particles will be __________________ the
pressure from Test #2.
3
200 Heavy particles =
Pressure for 100 Light AND 100 Heavy particles will be
__________________ the pressure from Test #3
4
5
6
100 Heavy + 100
Light particles =
Pressure for 200 Heavy AND 100 Light particles will be
200 Heavy + 100
Light particles =
Pressure for 150 Heavy AND 50 Light particles will be
100 Heavy + 50 Light
particles =
Write your own prediction:
__________________ the pressure from Test #4.
__________________ the pressure from Test #5.
1. For Test 6 (100 Heavy + 50 Light particles), what is the pressure contribution from the heavy
particles (Pheavy)? How did you figure this out?
2. What is the pressure contribution from the light particles (Plight)? How did you figure this out?
3. Whose gas law is represented by this simulation?