Comparing Temperature Scales

Engage

Although students are familiar with the word temperature, they do not necessarily understand what temperature is measuring.  Although temperature and heat are related, they are not interchangeable. 

Pose the following discussion questions to students to get them to think about temperature:What is temperature?  What does the temperature of a substance tell us about it?  What is the difference between temperature and heat?

Explore

Open the Excelet “Temperature Scales” using Microsoft Office Excel.  Click on the tab labeled “Model 1.”  Use the sliding bar to move the temperature up or down.  Record (type in) at least 5 data points on the yellow data table provided.   Warning!  Only type in yellow boxes. Analyze the relationship carefully and answer the following questions:

   1. When Kelvin temperature is 400, what is Celsius?
   2. When Kelvin temperature is 400, what is Fahrenheit?
   3. When Celsius temperature is zero, what is Kelvin?
   4. When Celsius temperature is zero, what is Fahrenheit?
   5. As Kelvin temperature increases, what happens to the other temperatures?
   6. Do they appear to be affected the same?
   7. For a change in temperature of 1 K, what is the change in ºC?    

(check answer on computer)

   1. For a change in temperature of 1 K, what is the change in ºF?  

(check answer on computer)

Explain

Once you have finished with Model 1, click on the tab labeled “Model 2.”  Analyze the relationship carefully and answer the following questions:

   1. What type of function do these graphs illustrate?  (linear, quadratic, cubic)
   2. Choose two points from the Celsius vs. Kelvin graph and calculate the slope.
   3. Now use the slope and one of the points to determine the formula for the graph.
   4. Choose two points from the Fahrenheit vs. Celsius graph and calculate the slope.
   5. Now use the slope and one of the points to determine the formula for the graph.
   6. Where does the Celsius vs. Kelvin graph cross the y-axis?
   7. Where does the Fahrenheit vs. Celsius graph cross the y-axis?
   8. What is the conversion formula to convert Celsius to Kelvin?
   9. What is the conversion formula to convert Kelvin to Celsius?
  10. What is the conversion formula to convert Fahrenheit to Celsius?
  11. What is the conversion formula to convert Celsius to Fahrenheit?
  12. Write a formula to convert Fahrenheit to Kelvin.

Elaborate

Now that you have explored temperature scales using a mathematical model, you will collect some data and see if the experimental data matches the mathematical prediction.  Collect the following equipment:

    * 2 Styrofoam Cups

    * Beaker

    * Hot Plate
    * Thermometer

    * Ice water

    * Data collection devices such as Vernier’s LabPro
    * Data analysis software such as Vernier’s LoggerPro
    * 2 temperature probes for the data collection device

1.   Measure about 150 mL of tap water into a beaker and heat it to at least 50°C on a hot plate.2.   While the water is heating, set up the data collection device and connect it to the computer.  Plug the two temperature probes into the device.  Set one probe to record temperature in Celsius and the other in Fahrenheit.  Set up the data analysis software so that the Fahrenheit temperature is on the y-axis and the Celsius temperature is on the x-axis.3.   Pour the hot water into a Styrofoam cup.  Measure 150 mL of the ice water into a different Styrofoam cup.4.   Place both temperature probes into the hot water and begin collecting data.  Once the temperature reading has stabilized, quickly move the probes from the hot water to the ice water.5.   Continue to collect data for 30 seconds after the probes have been moved.6.   Once you have finished collecting data, use the data analysis program to analyze the graph.  Find the equation of the line formed while the temperature was changing.7.   Record the equation.  Cut and paste the graph and data table into a Word document.8.   Report the results of your investigation on the class wiki.  For more information about wikis, watch the video “instant Publishing” at http://www.nortellearnit.org/technology/Webpage_Creation/  Each lab group should link their own page off of the main page.  Use the rubric to guide your report writing.  Be sure to include the graph and data table you saved as well as the equation generated by your data.  Compare your experimental results to the mathematical prediction in your Conclusion.

Extend

To challenge students further, have them complete Model 3 in the “Temperature Scales” Excelet (deriving the relationship of the Rankine temperature scale to the Celsius, Fahrenheit, and Kelvin scales) or the “Inventing” tab (students invent their own temperature scale).