Heat and Pressure-Volume Work Tutorial

Tutorial for Experiment: Heat and Pressure-Volume Work

EXAMPLE: What changes in the pressure, temperature, and mean square velocity of the ideal gas will occur with the removal of heat from the gas in a constant volume process and how are these changes related?

EXPERIMENT: Use the applet to determine the temperature, pressure, and mean square velocity of the ideal gas in a cylinder with a fixed volume. Place the cylinder in a cold bath and after two minutes again determine the temperature, pressure, and mean square velocity of the ideal gas.

PROCEDURE:

  1. Select "Isochoric" (constant volume) from the External Pressure pull-down menu and "Remove" from the Heat pop-up menu.



  2. Click the Start button to initiate the animation.



  3. The cooling process begins with the appearance of the mean square velocity near the bottom of the cylinder. Record the mean square velocity.



  4. Allow the animation to run for an additional two minutes after the appearance of the mean square velocity. Record the mean square velocity.



  5. Click the Stop button and record the initial and final pressures, temperatures, and volumes.





RESULTS and OBSERVATIONS: The pressure, temperature, and mean square velocity decrease with the cooling of the ideal gas.

Explanation: The gaseous atoms lose kinetic energy when they collide with the cold cylinder wall. As the mean kinetic energy, , of the atoms decreases, the mean square velocity, , decreases and hence the pressure, , and temperature, , decrease in a constant volume process.