Temperature Probe Response Time Laboratory


This experiment is designed for the beginner with detailed instructions. Performing this lab will allow you to become familiar with the Temperature Probe, ChemBio and Physics programs with CBL and TI Graphing Calculators so that teachers and students can design their own labs and inquiry activities.

You will notice icons scattered througout the lab instructions. Clicking on the icon will pull up a window with
  • information and helpful hints
  • sample calculator screens
  • pictures of the equipment or experiment
Introduction
Thermometers are used extensively in science labs of all types and are an easy source of data for math students. The temperature response time is the time it takes a thermometer or temperature probe to reach equilibrium with its surroundings. It is necessary to know the response time of the instrument you are using in order to take timely, accurate measurements.
Materials a
CBL Unit ice water (~0oC)
Temperature Probe ........ hot water (~70oC)
TI Graphing Calculator (73, 81, 82, 83 or 83+)
(with Physics or ChemBio program or application)		 two 250 mL beakers
Link Cable

Procedure
  1. Place about 100 mL of ice water into a 250 ml beaker

  2. Place a temperature probe into the cold water and stir for a few seconds. Leave the probe in the water while you set up the CBL and calculator.

  3. Plug the temperature probe into Channel 1 of the CBL unit. Connect the CBL to the TI Graphing Calculator with the black link cable using the port on the bottom of each unit. Make sure the connection is tight by pressing firmly.

  4. Turn on the CBL unit and the calculator.

  5. Press PGRM and select CHEMBIO or PHYSICS. Press ENTER, then ENTER again to get to the MAIN MENU.

  6. Set up the calculator and CBL for one temperature probe.
    • Select SET UP PROBES from the MAIN MENU
    • Enter 1 as the number of probes
    • Select TEMPERATURE from the SELECT PROBE menu.
    • Enter 1 as the channel number.

  7. Set up the calculator and CBL for data collection.
    • Select COLLECT DATA from the MAIN MENU
    • Select TIME GRAPH from the DATA COLLECTION menu
    • Enter 4 as the time between samples in seconds
    • Enter 25 as the number of samples (the CBL will collect data for a total of 100 seconds).
    • Press ENTER, then select USE TIME SETUP to continue.
    • Enter 0 as the minimum temperature (Ymin).
    • Enter 80 as the maximum temperature (Ymax)
    • Enter 10 as the temperature increment (Yscl)
    • If you are using the PHYSICS program, you need to select LIVE GRAPH.

  8. Get about 150 mL of hot water in a second 250 mL beaker. Read the next 2 steps before proceeding!

  9. With the temperature probe still in the cold water, press ENTER on the calculator to start collecting data. Do not stir or move the water.


  10. When exactly 20 seconds have passed (when the 5th data point appears on the calculator screen), quickly move the temperature probe to the beaker of hot water and finish collecting data. Do not stir or move the probe while the CBL is collecting data.

  11. When data collection is complete press ENTER to display the temperature vs. time graph on the calculator screen. Use the left and right arrow buttons in the upper right hand corner of the calculator to examine the data points along the curve.

  12. To view a list of the temperature data:
    • Press ENTER then select NO when asked if you want to repeat the trial.
    • If you are using ChemBio select VIEW DATA from the MAIN MENU
      If you are using Physics select QUIT
    • Press STAT and choose EDIT
Analysis and Questions
  1. Determine the response time of your temperature probe or the time it takes to reach the maximum temperature after being switched from the cold water to the hot water. Use the graph and the data list. Do you get the same answer?

  2. List and describe some factors that might affect the response time of a temperature probe.

  3. How might a temperature probe with a shorter response time be constructed?

  4. Advanced (TI 82, 83 and 83+ only):Describe the curve of your graph. What type of function (if any) do you think would describe this curve? Use the calculator to try a few.
    • Quit the ChemBio or Physics program
    • Press STAT and choose CALC from the menu across the top of the screen. Choose from the available options such as a linear regression (LinReg), quadradic regression (QuadReg), cubic regression (CubicReg), exponential regression (ExpReg), power regression (PwrReg) and more.
    • Press L1 (2nd-1), comma, L2 (2nd-2), comma.
    • On the TI 83 and 83+ press VARS and choose Y-VARS. On the TI 82 press Y-VARS.
    • Choose Function and Y1.
    • Press ENTER to view the equation and R2 value.
    • Press GRAPH to see a graph of your data with the regression line

Sample Data and Graph

Time (seconds)
Temperature
(oC)
Time (seconds)

Temperature
(oC)
4
15.5
56
77.5
8
15.5
60
77.8
12
15.5
64
77.8
16
15.5
68
77.8
20
15.5
72
77.8
24
45.8
76
77.8
28
63.8
80
77.5
32
70.2
84
77.5
36
73.3
88
77.5
40
75.2
92
77.2
44
76.2
96
77.2
48
76.8
100
76.8
52
77.2