Ideal Gas Laws - General Physics II - Laboratory 2 Report | PHYS 102, Lab Reports of Physics

Download Ideal Gas Laws - General Physics II - Laboratory 2 Report | PHYS 102 and more Lab Reports Physics in PDF only on Docsity! Longwood University – Physics 102 Lab Manual 7 Introduction The ideal gas law is an equation of state that describes the relationship between the pressure (P), the volume (V), the number of molecules (n) and the temperature (T) of an ideal gas. This relationship is as follows: nRTPV = (1), where R is a constant. Although real gases do not behave exactly like an “ideal” gas, they do behave similarly enough that we can use Equation 1 to describe their behavior. It is important to point out (and most students miss this insight) that Equation 1 describes the relationship between four different variables. Typically, students will only consider two variables at a time, such as pressure and volume, and ignore the other variables, such as number of molecules and temperature. The ideal gas law also does not distinguish between different species of gases (such as hydrogen and oxygen). Many students attempt to account for the size or mass of individual molecules when dealing with ideal gases; however, the relationship described by Equation 1 references the number of molecules, and not the type of molecules. In this lab, you will proceed through a series of “thought experiments” to help develop the concepts of pressure, temperature and volume. Activity 2 will focus on how the ideal gas law does not discriminate among species of gases. The principles in this lab should reinforce the following concepts: • Pressure, volume and temperature • The ideal gas law • The relationship between thermodynamic variables Experimental Procedures Activity 1: Tutorial on Pressure and the Ideal Gas Law Equipment: computer with internet access (1) Complete the Data Analysis sheet for Activity 1. (2) You may find the interactive simulation at the following website useful in answering these questions: http://phet.colorado.edu/new/simulations/. Click on “Heat and Thermo” and then click on “Gas Properties”. Running the simulation will allow you to “play” with the various thermodynamic variables and their influence on each other. Lab 2: Ideal Gas Law Longwood University – Physics 102 Lab Manual 8 Activity 2: Tutorial on Avagodro’s Number and the Ideal Gas Law Equipment: pencil, paper, brain (1) Complete the Data Analysis sheet for Activity 1. (2) You may find the interactive simulation at the following website useful in answering these questions: http://phet.colorado.edu/new/simulations/. Click on “Heat and Thermo” and then click on “Gas Properties”. Running the simulation will allow you to “play” with the various thermodynamic variables and their influence on each other. This lab adapted from Tutorials in Physics by Lillian McDermott. Contents copyright © Prentice-Hall 2002. Longwood University – Physics 102 Lab Manual 11 10. Is Vf greater than, less than, or equal to Vi? Is your answer consistent with the ideal gas law? 11. For the process described above, circle the variables that are held constant. Explain how you can tell in the space below. PRESSURE VOLUME # MOLECULES TEMPERATURE Consider the following discussion between two students: Student 1: “According to the idea gas law, the pressure is proportional to the temperature. Since I increased the temperature of the gas, the pressure MUST go up!” Student 2: “That right! Since no gas entered or left the system, the volume did not change. So the pressure must have increased.” 12. Both students are WRONG! In the space below, explain why based on your answers from above. Activity 2: Tutorial on Avogadro’s Number and the Ideal Gas Law Two identical cylinders just like the ones from above contain hydrogen and oxygen, respectively. Both cylinders have been sitting in the same room for a long time. Their pistons are at the same height as seen in Figure 5. Figure 5: Two cylinders filled w/ hydrogen and oxygen, respectively. H2 O2 Longwood University – Physics 102 Lab Manual 12 13. Compare the volumes of the gases in the two cylinders. 14. Compare the temperatures of the gases in the two cylinders. 15. Compare the pressures in the two cylinders. (Remember the equation you developed in question 6!) 16. Compare the number of moles in the two cylinder. Consider the following discussion between two students: Student 1: “Since hydrogen molecules are so much smaller than oxygen molecules, there should be more of them in the same volume.” Student 2: “No! Since n = 2 for hydrogen, and n = 32 for oxygen, there must be more oxygen molecules.” 17. Once again, both students are WRONG! Explain why based on your answers above. This lab adapted from Tutorials in Physics by Lillian McDermott. Contents copyright © Prentice-Hall 2002.