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Measuring Absolute Zero in Celsius

     The investigations of Charles and Kelvin led to the discovery of the temperature value at which all motion ceases (absolute zero). This value required careful measurement and the realization by Kelvin that a temperature in which a gas has a volume of 0 Liters means that the particles in the gas no longer move.

     This experiment will attempt to measure the value of absolute zero. The slope of the line from the graph of volume (mL) versus temperature (^oC) will be used to find the value of the temperature at a volume of 0 mL.

Materials per Group

One 3 or 5 mL disposable syringe, one cap of vegetable oil, one celsius thermometer, four containers of about 1 Liter volume.

Procedure

1.  Dip the end of the syringe plunger into a small amount of vegetable oil. Insert the plunger into the syringe barrel and move the plunger up and down several times to lubricate the syringe.

2.  When the plunger moves freely inside of the syringe, fill the syringe to the 2.0 mL mark.

3.  Use epoxy glue or heat to seal the open end of the syringe.

4.  Test the syringe to make sure the seal is airtight. The plunger should return to the 2.0 mL mark on the syringe after it is pushed or pulled.

5.  When the syringe is ready, submerge it into a beaker of ice water. Allow the syringe to equilibrate in the ice water for about 3 to 5 minutes. Record the temperature of the ice water. Move the plunger up and down then release the    plunger. Read the volume of gas that the plunger returns after it is released. Pull up on the plunger and release it. Check the volume to make sure the plunger returns to the same spot. When you are satisfied that the syringe is giving a reliable value for the gas volume in ice water, record the volume in the table below.

6.  Place the syringe in a beaker of room temperature water. Use the same procedure for measuring the gas volume that was used in step 5.

7.  Repeat this process for a beaker in warm water and for a beaker in hot water. In the end, you should have a minimum of one reading for each of the four temperatures. If time permits, measure a second set of volumes and        temperatures (T5 through T8).

Graphical Method for Finding Absolute Zero

Plot the temperatures in degrees Celsius on the vertical axis. Plot the gas volumes on the horizontal axis. The temperature at the horizontal intercept is the temperature at zero volume or absolute zero.

Data Table

Calculation Table

Subtract the volumes as indicated on the table and divide by the difference in

Temperature. Express answers to the nearest 0.1.

Calculate one average value for the change in volume per 1 Celsius degree.

To find the value at a volume of 0 mL, select a temperature and volume from the table. For example, suppose the volume of gas at 25^oC was 10.0 mL. Suppose the average value for change in volume per Celsius degree was 0.038 mL /  ^oC. This means that for every 1^oC drop in temperature, the volume drops 0.038 mL. How many ^oC it will take to drop from 10.0 mL to 0.0 mL starting at 25^oC.

25^oC  - 10 mL (1^oC) =     -238^oC.

                (0.038 mL)

The calculated value for the temperature of absolute zero is -238^oC.

Calculate the value of absolute zero for each of the four temperatures that were used.