Testing the effect of insulators on the rate of cooling of water

Introduction

DrDAQ is used here with the two external temperature probes, one for the control and one for each of the insulated containers. This experiment looks at the effectiveness of different materials in reducing the loss of heat energy from a container (boiling tube). Students should know how to carry out a fair test and have some knowledge of conduction. More advanced students should be able to discuss radiation and evaporation.

The experiment could be set as a challenge e.g. if you were planning an investigation to Antarctica what materials would keep you warmest? This investigation could then form a part of a larger investigation into explorers, adaptations of organisms for different climates and food. The experiment is suitable for students of 11 and over.

Equipment required

• DrDAQ data logger connected to a PC
• Two external temperature probes
• 12 boiling tubes
• Measuring cylinder
• Test tube rack
• Kettle
• Elastic band
• A selection of materials. We used:
  • Bubble wrap
  • Aluminum foil
  • Polystyrene (Styrofoam)
  • Dry paper towel
  • Wet paper towel

Experiment setup

• Plug the pH probe into DrDAQ and run PicoLog data logging software.
• Cover 6 boiling tubes with insulating material and secure with an elastic band.
• Boil a kettle and pour 40 cm³ of water into two boiling tubes. Take care with the hot water.
• Place one external probe into each of the boiling tubes and start recording. This needs to be done as quickly as possible.

Questions and discussion of results

1. Which insulating material kept the water warmest?
2. Why do you think this material kept the water warm?
3. In which boiling tube did the water cool most quickly? Why do you think this is?
4. Were any of the results different from what you expected? Why?
5. Was the experiment a fair test? Could it have been improved? How?
6. If you were lost on a mountain it is important that you stay dry. Why do you think this is?
7. Why does sweating cool you down?

Further study

• Students could calculate the drop in temperature for each experiment.
• Instead of using the materials suggested here the students coats could be used and therefore a comparison of their effectiveness made.
• Penguins keep warm by huddling. They constantly move so that each penguin gets a time in the centre and edge of the group. Students could design an experiment to test the effectiveness of huddling in keeping organisms warm.
• Which keeps you warmer, one thick layer or many thin layers.