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?