Physlet Illustration: Charles' Law

 

 

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A piston floats atop a cylinder filled with an ideal gas. The cylinder is surrounded by a constant temperature bath. Each grid in the animation represents a volume of 10 cm3. 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 volume changes. The graph shows volume (in cm3) vs. temperature (in Kelvins). Can you verify Charles' Law? How many moles of gas are in the cylinder?

Hints:

  1. What happens to the volume as the temperature of gas increases?
  2. Pause the animation and determine T (in Kelvins) and V at some instant. Find the ratio V/T.
  3. Pause the animation again and determine V/T. Does this ratio remain constant?
  4. Convert P into Pa (i.e. N/m2), V into m3 and T into Kelvins.
  5. Using PV = nRT, then, can you calculate the number of moles of gas?

Reference

See Walker, Section 17-1

Illustration written by Steve Mellema