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Two temperature sensors can collect some interesting information about a change of
state during cooling. In this experiment the temperature of a water bath increases as a
substance cools. The setup will also show that, during the change of state, heat is lost
from the substance even though its temperature remains constant.
Setting up
 | Connect two temperature sensors to channels 1 and 2 on the interface. |
| Place one temperature probe in a test tube half-filled with stearic acid. |
| Warm the tube and probe in a water bath to melt the stearic acid.
|
Apparatus
| Beaker |
| test tube |
| water bath |
| insulation material for the beaker |
| stearic acid (or wax; benzophenone) |
| test tube rack |
| interface |
| temperature sensors
|
Sensor identification
The software needs to know that you have connected two temperature sensors. Set them on
their 0-100 range if they are adjustable. Some systems identify sensors automatically.
Recording the data
| Remove the tube from the water bath. |
| Place it in a small insulated beaker, partly filled with water. |
| Record for 20 minutes. |
| Stir the stearic acid continuously. |
Using the results
| How does the graph show you that the stearic acid is getting cooler? |
| What happening to the water as this occurs? |
| Why is this? |
| What is happening to the stearic acid when the graph is flatter? |
| What happening to the water as this occurs? |
| Where does the water gain its heat from? |
The IT in Science book of Datalogging and Control, R. Frost
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