4E30.10 Constant Volume Gas Thermometer


Ideal gas law, absolute zero


Measurements of pressure at different temperatures with a fixed volume can be graphed to demonstrate the ideal gas law and absolute zero.



  • [1] Gas thermometer
  • [1] Lab stand
  • [1] 90-degree clamp
  • [1] 3-finger clamp
  • [2] 2000 mL beaker
  • [2] Dewar
  • [1] Mercury thermometer (-20 to 110 C)
  • [1] Alcohol thermometer (-100 to 50 C)
  • [1] Thermocouple
  • [1] Hot plate or kettle
  • [1] Ice scoop
  • [1] Bucket of water
  • Water ice
  • Dry ice
  • Ethanol
  • Liquid nitrogen

Safety Equipment

  • [1] Safety goggles
  • [2] Safety glove

Classroom Assembly

  1. Put the ethanol in a dewar and pre-cool it with dry ice.
  2. Put the liquid nitrogen in the other dewar.
  3. Put water and ice in a beaker.
  4. Put water in the other beaker. Heat the water on the hot plate, if desired, or use the kettle.
  5. Mount the gas thermometer on the lab stand using the 90-degree clamp and 3-finger clamp.

Important Notes

  • Be careful when putting anything into a dewar. The inside of the dewar is made of fragile glass.
  • Liquid nitrogen, dry ice, dry ice in ethanol, and hot water can cause severe burns and blindness. Use with caution.
  • Watch the hot plate or kettle to make sure the water doesn't boil out of control.


  1. Put on your safety goggles and gloves.
  2. Read the room temperature from a thermometer and the pressure in the gas thermometer.
  3. Repeat step 2 with the gas thermometer immersed in the various media: liquid nitrogen, dry ice in ethanol, ice in water, and hot water. For the liquid nitrogen, use a thermocouple to measure temperature.
  4. Plot P vs. T and extrapolate it to absolute zero at P = 0.


Additional Resources


  • PIRA 4E30.10
  • DHP Ha-4; Meiners 25-2.7; Disc 16-02


  • Don't attempt this at home!

Last revised

  • 2020


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If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.