DON T LOSE YOUR TEMPERATURE Don t Lose Your Temperature Student Instruction Sheet Challenge When the temperature remains constant, how does the pressure of a gas in a rigid container change as the volume changes? Equipment and Materials computer with USB port tubing (with sensor) PASPORT USB interface glycerin (C 3 H 5 (OH) 3 ), 1 drop PASPORT Absolute Pressure Sensor protective gear DataStudio software Student Instruction Sheet syringe (with sensor) Student Response Sheet quick-release connector (with sensor) Safety Precautions Remember, follow the directions for using the equipment. Avoid over-compressing the air in the syringe in order to minimize the risk of injury or damage to the equipment. Wear safety glasses and follow all standard laboratory safety procedures. Student Instruction Sheet 113
Background D ON T LOSE YOUR TEMPERATURE The relationship of pressure to volume for a gas in a rigid container was first described in 1662 by the Irish-born scientist Sir Robert Boyle (1627-1691), and is known as Boyle's Law. As long as the temperature of the gas remains constant, the pressure of a gas has a predictable relationship with the volume of the gas. The pressure of a gas is a measure of the force the gas exerts on the walls of its container. What causes a force to be exerted? Recall that the particles (atoms or molecules) the gas is made of are in constant motion, colliding with each other and with the walls of the container they occupy. The net effect of these collisions is pressure. Even if a gas is not contained, the force of collisions results in pressure. For example, the air around us exerts a force on every object it touches, and we measure this atmospheric pressure with a barometer. In this activity, the gas (air) you will be investigating will be contained in a plastic syringe tube, which will be connected at the "needle end" to a Pressure Sensor. Think about how a syringe works. What will happen to the volume of air inside the syringe as you push the plunger down? How will the gas molecules inside the syringe respond as the plunger is depressed? Also, think about what will happen once you stop pushing down on the plunger. How will the volume inside the syringe change? What will happen to the air pressure then? Predict Before beginning the elab, complete the prediction portion and define the vocabulary words on the Student Response Sheet. Explore Computer Setup 1. Plug the USB interface into the computer s USB port. 2. Plug the Absolute Pressure Sensor into the USB interface. This will automatically launch the PASPORTAL window. To computer 114 Student Instruction Sheet
DON T LOSE YOUR TEMPERATURE 3. Choose the appropriate DataStudio configuration file entitled 04 Boyle s Law CF.ds and proceed with the following instructions. Equipment Setup Note: Configuration files automatically launch the appropriate display(s), sampling rate(s), etc. 1. Put a drop of glycerin on the barb end of a quick-release connector. Put the end of the connector into one end of a short piece (about 2.5 cm) of plastic tubing that comes with the Absolute Pressure Sensor. 2. Put a drop of glycerin on the end of the syringe. Connect the end of the syringe to the other end of the small piece of plastic tubing. Connector Syringe Tubing 3. Adjust the volume of air in the syringe to 20.0 ml. 4. Align the quick-release connector on one end of the plastic tubing with the pressure port of the Absolute Pressure Sensor. Push the connector onto the port, and then turn the connector clockwise until it clicks (about one-eighth turn). 5. Check that the syringe and pressure sensor have a secure seal by adjusting the volume from 20.0 ml down to 10.0 ml. (It should get harder to push the plunger as the volume decreases.) Student Instruction Sheet 115
D ON T LOSE YOUR TEMPERATURE Record Data 1. Click the Start ( ) button to begin recording data. The Start button will change to the Keep ( ) button, and the Table Display will show the value for pressure when the volume is 20.0 ml. 2. Click Keep to record the pressure. Note: The Table Display will change to show the next value of volume (18.0 ml). 3. Move the plunger to the 18.0 ml mark and click Keep to record the pressure. 4. Continue to move the plunger to each new position and then click Keep to record the corresponding pressure. 5. After you record the pressure for the last volume, click the Stop ( ) button to end data recording. Analyze Record calculations in your data table on the Student Response Sheet as you complete your analysis. 1. Use the Graph Display to examine the plot of Pressure versus Volume and also the plot of Pressure versus Inverse Volume for the data you gathered. 2. Use the Table Display to examine the Pressure and Volume. 3. Save your DataStudio file (on the File menu, click Save Activity As...) to the location specified by your teacher. 4. Answer all the questions on the Student Response Sheet. 5. Follow your teacher s instructions regarding cleaning up your work space. 116 Student Instruction Sheet
DON T LOSE YOUR TEMPERATURE Student Response Sheet Name: Date: Don t Lose Your Temperature Vocabulary Use available resources to find the definitions of the following terms: compressible: gases: kinetic energy: liquids: pressure: solids: volume: Student Response Sheet 121
Predict D ON T LOSE YOUR TEMPERATURE How does the pressure of the gas inside a syringe change as the syringe plunger is pushed down? Data Make a sketch of your graph of Pressure versus Volume and a sketch of your graph of Pressure versus Inverse Volume (InvVol). Analyze In your graph of Pressure versus Volume, use the Fit ( mathematical fit for your data. ) menu to find a 1. Based on your pressure-versus-volume data, how is the pressure proportional to the volume? 122 Student Response Sheet
DON T LOSE YOUR TEMPERATURE In your graph of Pressure versus Inverse Volume, use the Fit menu to find a mathematical fit for your data. 2. Based on your pressure-versus-inverse volume data, what is the relationship of pressure to the inverse of volume? 3. Using the graph of Pressure versus Volume, how does the pressure at 10.0 ml of volume compare to the pressure at 20.0 ml of volume? (Hint: Use the Smart Tool.) Synthesize 1. Boyle's Law describes the relationship between gas pressure and volume at constant temperature. Did the experimental conditions in this investigation include the feature of constant temperature? How might this factor relate to experimental error in your data? 2. Do your results support your predictions? Why or why not? Student Response Sheet 123
D ON T LOSE YOUR TEMPERATURE 124 Student Response Sheet