Learning Exercise

Gas Process Practice

Let students make predictions and perform online tests of their results. Interactive exploration of Ideal Gas PV transformations.
Course: Physics 2 for Scientists and Engineers
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This applet presents a simulation of four simple transformations in a contained ideal diatomic gas. The user chooses the... see more

Exercise

Things to do: Compute the changes in thermodynamic quantities for the different processes, and check your results:


Number - How many moles of ideal gas are in this simulation? (This is, in fact, noted below the applet. Try to figure this out before looking.)


Isobaric - Compute the heat needed to raise the volume by 50 cc for a specific pressure and check your result. (Note: To set the pressure to something easy to work with, go to the isothermal process, grab the piston, and move it up or down until you obtain the pressure you desire. Then go back to the constant pressure process and clear the graph.) Note that the temperature can not be raised above 200 K by adding heat for this process.
Next, compute the change in temperature if you increase the volume by 50 cc, by grabbing the piston and moving it.


Isochoric - Compute the heat needed to raise the pressure by 30 kPa at constant volume and check your result. Again, you can set your starting point by moving the piston in an isothermal process and the temperature can not be raised above 200 K by adding heat for this process.


Isothermal - How much do you need to change the volume in order to double the pressure of the gas? How much heat is exchanged in this process? (Note: You can't really check this last question using the applet, but you should be able to answer it.)


Adiabatic - How much do you need to change the volume in order to double the pressure of the gas? Why is this different from an isothermal process?


More difficult

Engine Design - Comput the endpoints (P, V, and T) of an engine with the following three processes: Isothermal expansion from V1 to 3 V1 (picking a fairly large initial value of P, around 120 kPa), Constant volume change in pressure, then adiabatic compression back to your original point. You need to compute the final pressure of the second step in order for the cycle to be closed. Use the applet to show that your result is correct.


How does working with a diatomic ideal gas change your answer? Show this.

Audience

Requirements

Part of thermodynamics module in the course. Requires previous study of Thermodynamics, Ideal Gas Law, and processes.

Learning Objectives

Make and test predictions from physical models.

Understand qualitative features of Ideal Gas processes.