Measurement of Absolute Zero using Charles’ Law
PLEASE DO NOT WR ITE ON THIS
PAPER, PLEASE RETURN FOR REUSE
The idea of this procedure is to capture heated air in a flask and then cool it to see how much the volume changes.
Start by making sure your flask is dry, if not dry it by gently heating over the Bunsen burner.
The air in the flask is heated by with the flask which is partially submerged in the boiling water. Once heated for a
sufficient time the flask is closed to capture the air. This will be the original volume (Vhot) which you will measure
later. The temperature of the boiling water is close to the temperature of the air in the flask (Thot) so this is the
temperature that you should measure and record for your original temperature (Thot).
Once you have captured the air allow the flask to cool in the room temperature air for several minutes.
You will now cool the air in the flask and its volume will decrease. Cool the flask by putting it in the ice bath. Cool
the flask for 15 minutes or more. Then turn the flask upside down (stopper down) and open it so the water can take the
space left by the air of decreased volume. Once water is in and cooled close the flask off. You will measure the
quantitiy of water captured (V). Measure the temperature of the ice bath, this is the temperature of the cooled air
(Tcold).
To find the change in volume (V) , measure the volume of the water captured. To measure the original volume
(Vhot), fill flask with water and use a graduated cylinder to see how much is in it. The volume of the cooled are is
given by the equation Vcold = Vhot - V
STEP BY STEP
1. Check that flask is dry to start with, if not take stopper out and heat it gently over Bunsen Burner.
Allow to cool.
2. Replace stopper with hose open.
3. Heat about 200-250 ml of water in beaker to boiling with flask (valve or hose open) mostly
submerged in the water. Allow to boil for 10-15 minutes.
4. After heating use pinch clamp to close hose. Remove from heat.
5. Measure and record temperature of water (Thot)
6. Allow flask to cool for 5 minutes in the room temperature air.
7. Further cool flask in ice bath for 10-15 minutes.
8. Turn flask upside down (stopper pointed towards bottom of ice bath).
9. Hold flask about half submerged in water.
10. Open valve to allow water in space of cooled air. (It is best to move the flask so the height of the
water inside matches the height of the water outside)
11. Close valve to capture water.
12. Measure and record temperature of ice bath (Tcold).
13. Notice how far in the bottom of the stopper goes and then remove.
14. Measure and record volume of water captured in flask with graduated cylinder (V) .
15. Fill flask to height of where the bottom of the stopper came down to and measure the volume of this
water with the graduated cylinder (Vhot)
16. If time allows complete the lab for a second trial to attempt to improve upon your data.
Record your measurements on your own piece of paper. They should be as follows:
Trial
Vhot
Thot
1
2
<<SEE NEXT PAGE>>
V
Tcold
LAB REPORT & CALCULATIONS
GRAPH THE DATA AND SKETCH THE TREND TO FIND THE X-INTERCEPT
To calculate Asolute Zero you will need to two points that can be plotted on a graph. These are
X-axis
Y-axis
Tcold
Thot
Vcold
Vhot
Remember, you will need to calculate this
value from the equation Vcold = Vhot - V
Use the values above to make an X-Y Scatter plot in Excel. Be sure to adjust the x-axis scale so there will
be enough room that you will be able to see where the trend line crosses the x-axis. (A low value for the xaxis of –300 should be enough)
USE THE DATA TO ALGEBRAICALLY FIND THE VALUE OF ABSOLUTE ZERO
You did an example of this on a previous homework. Please see that, a math teacher or myself for help on
this. You should be able to do this, be sure to write this out completely with explanation of what your
doing.
CALCULATE YOUR PERCENT ERROR
% Error 
| Your _ Value  Actual _ Value |
 100%
| Actual _ Value |
Do not expect low values for percent error.
is