Statistics: Graphing Absolute Zero

The Stats class used Flinn's Charles' Law Lab instructions today.  I wanted a real life example of collecting data and using the data to extrapolate.  We measured the volume of air (gas) in a syringe at different temperatures.  Basically, the syringes are in yogurt containers filled with ice water, boiling water, and room temperature water.  I had the kids mix the hot water with cold to get at least four or five data points.  We used 10 mL and 30 mL plastic, oral syringes with caps.

We found that the 30 mL syringes didn't work.  I insisted I needed 30 mL syringes--not just 10 mL syringes.  Guess what?  The 10 mL syringes worked better.  The results were surprising.


Here is one student's, Anna's, data:
Temp  (C)   Vol (change in volume mL)
19.5              5.5
13.3              5.0
9.4                5.5
63.8               7.0
30.6              6.25


Next the kids plotted, calculated, and graphed the linear regression with their TI 83/84 calculators.  Then, the kids went to the Window in the calc and extended the range: Xmin -300, Xmax 100, Ymin 0, Ymax 10.

Lastly the kids extrapolated to see the temperature at 0 volume.  Anna's 0 volume y-intercept was -360C.  Absolute zero is -273.15.  Her percent error is 32%.  Not bad at all!  We had a couple students with less than five percent error.  That was excellent and unexpected.  Remember we used syringes in yogurt cups for the water bath.

The lab coincides with Chapter 4 in Stats.  How do you collect, organize, graph, and present your data?

I'll post a lab report when the kids finish.