Physlet Illustration: Kinetic Theory and an Ideal Gas

 

 
A piston is clamped in place at the top of a cylinder filled with an ideal gas. The cylinder is surrounded by a constant temperature bath. A digital temperature probe which reads the gas temperature in °C, is attached to the cylinder. A digital pressure sensor, which reads the pressure in kPa, is also attached. Play the animation to heat the temperature bath, and see how the pressure changes. The enlarged view shows the motion of some of the molecules inside the cylinder. How does their motion vary with changing temperature?

Hints:

  1. Start the animation, with the (initially) cold temperature bath.
  2. While the temperature is relatively cold, how fast do the molecules seem to move?
  3. Once the temperature is hot, how fast do the molecules seem to move?
  4. What, then, is the (microscopic) reason for the (macroscopic) observed change in pressure as the gas is heated?

Reference

See Walker, Section 17-2

Illustration written by Steve Mellema