SaH: Amazing Soap

In this experiment, you will discover how air molecules react to heat. Using a microwave and a bar of soap, you will be able to visualize the affects of heat on these air molecules. Share a picture of your soapy-adventures!



What happens when you put a bar of Ivory soap in a microwave?



  • A bar of Ivory soap (the brand is important here as you need a bar of soap that is whipped with air)
  • Microwave
  • Bowl


What to Do

  1. Examine the bar of soap and make observations.
  2. If you have more than one bar of soap, place one in water. Does it float or sink?
  3. Place a bar of soap (not the wet one) in a bowl and microwave for 2 minutes.
  4. Carefully remove the bowl from the microwave and allow it to cool for a minute.
  5. Make more observations – what has changed?


What is Happening?

Ivory soap is whipped with air. As the temperature of gas increases, the volume of the gas increases as well. There is both air and water molecules trapped inside of the bar of soap. As they expand, so does the soap containing these gas pockets.

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