cart Shopping Cart cart(0)

Microwave soap

You will need:

  • A microwave-safe bowl
  • Household soap (wet soap works best, so use an old bar of soap from the shower)


  1. Place the bar of soap in a microwave-safe dish and zap it on high for between 30-60 seconds.
  2. You may need longer for low power microwaves.
  3. Watch as a foamy mass grows from the soap! (careful; do not touch until the soap is cool).

    ​Back to Kitchen Chemistry science experiments

    Back to heat experiments
microwave soap1

Why Does This Happen?

The water inside the soap is undergoing a phase change from liquid to water vapour, and expanding. The foamy effect also comes about from the expansion air bubbles trapped inside the soap. Basically by heating the soap and expanding water and air inside you end up with this lovely warm soapy foam. I used a small bar of soap and zapped it for about a minute. 

Be Amazing Book Front Cover; Ben Newsome, teacher & founder of Fizzics Education. Be Amazing -how to teach science the way primary kids love
Be Amazing!
How to teach science, the way primary kids love

Read more about Be Amazing
Want more ideas for teaching science?

Subscribe to the FizzicsEd Podcast!

Listen to FizzicsEd on Apple Podcasts

FizzicsEd podcast available on Stitcher

Join our newsletter for more science teaching thoughts & ideas

Join the Fizzics newsletter

​Back to Kitchen Chemistry science experiments

Back to heat experiments

>100 Free Science Experiments on this site!

Coloured shadows
  • Experiments to colour your class!
  • Easy & fun
read more
skeleton and student
  • Make fake blood & more!
  • Biology made simple
read more
electricity experiments
  • Circuit science for kids
  • Cheap materials found easily
read more
Vortex rings made with fog
  • Experiments using Newton's Laws
  • Step by step science
read more

School Science Visits: 

  • Highly engaging & curriculum-linked
  • Additional Teacher Support Resources
  • Professional visits in-class or via video conference
  • Both Primary School & High School science incursions
Call 1300 856 828 or use this form to discuss or make a show booking for your school!

Love Science?

Signup to our fortnightly email! Learn more

Contact us

1300 856 828

Unit 10/55 Fourth Ave
Blacktown, NSW 2148, Australia
facebook-icon Apple Podcast Icon  twitter-icon
linkedin-icon youtube-icon   pinterest-icon