This Ivory soap microwave experiment shows us how warmth impacts the water within the soap, making it grow and alter its form. Let's discover what occurs when we briefly microwave just a bar of Ivory soap!

First, you place the Ivory soap bar on a plate and microwave it for about 1-2 minutes. Ivory soap is unique because it has tiny pockets of air and water trapped inside. This is why it floats in water, unlike most other soaps.

picture of ivory soap bar for ivory soap in microwave kids fun science experiment


As you heat the soap in the microwave, the water molecules inside the soap get warmer and start moving faster. When water gets hot enough, it turns into steam, which is a gas.

When the water inside the soap turns to steam, it expands and takes up more space. This causes the soap to puff up and turn into a fluffy, cloud-like substance. The air pockets inside the soap also expand when the soap heats, contributing to the soap's fluffy appearance.

So, this experiment shows how heating the water inside Ivory soap can cause it to turn into steam, which then expands and changes the soap's shape and texture. By microwaving the soap, you get to see how heat can transform everyday objects in fascinating ways, teaching us about the effects of heat on water and substances like soap!

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A bar of Ivory soap: Ivory soap is specifically recommended for this experiment because it contains more air pockets than most other soaps, allowing it to expand more dramatically when heated.

A microwave-safe plate: Choose a plate that can safely be used in the microwave, as it will be used to hold the soap during the experiment.

A microwave oven: You will need a microwave to heat the soap and cause the expansion.

A knife or soap cutter (optional): To make the soap easier to heat evenly, you may want to cut it into smaller pieces before microwaving it. Make sure an adult handles the cutting process.

Oven mitts or a towel (optional): These can be used to handle the hot plate when removing it from the microwave.

Gather these materials, and ensure adult supervision is provided throughout the experiment to ensure a safe and enjoyable learning experience.


To ensure the safety of children while performing the exploding soap experiment at home, please follow these directions and safety precautions:

Adult supervision: Make sure an adult is present and supervising the entire experiment.

Prepare the materials: You will need a bar of Ivory soap (other soaps may not produce the same results), a microwave-safe plate, and a microwave.

Prepare the soap: Cut the bar of Ivory soap into smaller pieces to make it easier for the microwave to heat it evenly. Place the pieces on the microwave-safe plate.

Set the microwave: Place the plate with the soap pieces in the microwave. Set the microwave's power to medium or low, and set the timer for 1 to 2 minutes. The exact time may vary depending on your microwave, so keep an eye on the soap during the process.

Observe: Watch the soap erupt through the microwave window as it expands and turns into a soap cloud-looking structure. Do not open the microwave door until the process is complete.

Let it cool: Once the microwave has finished, wait for the adult to carefully remove the plate from the microwave. The soap and plate may be hot, so let them cool down for a few minutes before touching.

Clean up:  Let the soap cool; after it has cooled, you can touch and explore its new texture. When you're finished, dispose of the soap and clean the plate.

By following these steps and ensuring adult supervision, children can safely enjoy the exploding soap experiment at home while learning about heat transfer, gas expansion, and physical changes in matter.

Recycle & Reuse

Instead of throwing away the soap, consider these options of recycling it:

There are a few creative and useful ways to repurpose the expanded soap after the experiment:

Hand soap: Break the expanded soap into smaller pieces and place them in a soap dish near a sink. They can still be used as regular hand soap.

washing hands from recycled soap experiment

Soap flakes: Crumble the expanded soap into fine flakes and store them in a jar. These soap flakes can be used for various cleaning purposes, such as laundry soap or general household cleaning.

soap flakes to reuse from soap in microwave science experiment

Bath-time fun: Let your child play with the expanded soap during bath time. Its unique texture can be a fun sensory experience and has the added bonus of encouraging kids to wash themselves.

Bathtub fun recycling ivory soap explosion

Art projects: Use the expanded soap to create textured art projects. Allow your child to press the soap onto paper or cardstock to create interesting patterns and textures. You can also make some soap sculptures by wrapping small pieces of the expanded soap in toilet paper and shape then them into things like animals or abstract shapes. The toilet paper will provide additional support and structure, making it easier to create the sculptures.

art project from recycled ivory soap cloud

Soap Dough: Use the leftover pieces from the ivory soap science experiment to create an alternative to play dough or modeling clay, called soap dough.

Remember to ensure that the soap has cooled down completely before handling or using it for any of these purposes.

Science Is Fun!

Parents can make the exploding soap experiment more exciting and fun for their kids by incorporating the following ideas:

Make predictions:

Before starting the experiment, encourage your child to make predictions about what they think will happen to the soap when it's microwaved. This can spark curiosity and create a sense of anticipation.

Customize the soap:

Let your child choose their favorite color of Ivory soap or add a drop or two of food coloring to the soap pieces before microwaving them. This adds a personal touch and can make the results more visually appealing.

Turn it into a friendly competition:

If you have more than one child participating, have each child choose a piece of soap and see whose soap expands the most or creates the most interesting shape.

Time-lapse video:

Record a time-lapse video of the soap expanding in the microwave, and watch the transformation together afterward. This can help children visualize the process more clearly and make for a fun memory. This may be difficult with some microwaves and won't work for everyone.

Creative exploration:

Once the soap has cooled, allow your child to explore its new texture by touching, crumbling, or sculpting the fluffy soap. Encourage them to use their creativity and imagination while playing with the expanded soap.

Discuss the science:

After the experiment, engage your child in a conversation about the science behind the soap's expansion. Ask them questions and encourage them to think about what they learned from the experiment.

Relate it to real-life examples:

Help your child connect the concepts learned in the experiment to real-life examples, such as how popcorn pops or how bread rises when baked.

By incorporating these ideas, parents can make the exploding soap experiment more engaging, fun, and memorable for their children, while also fostering a love for science and hands-on learning.

Lessons Learned:

picture of soap bubbles

Gas Expansion

When you microwave the Ivory soap, the heat from the microwave causes the water molecules inside the soap to turn into steam (water vapor). As the water changes its state from liquid to gas, the steam expands because gas molecules occupy more space than liquid molecules. This is due to the fact that gas molecules move more freely and are less closely packed than liquid molecules.

The expansion of the steam creates pressure within the soap, forcing the soap to puff up and form a fluffy, cloud-like structure. This process demonstrates gas expansion because the soap's transformation is driven by the increase in volume of the water vapor (steam) inside the soap.

The exploding soap experiment is an excellent example of gas expansion, as it visually demonstrates how the change from liquid to gas (steam) results in an increase in volume, leading to the soap's dramatic transformation. That's not all though:

The exploding soap experiment is also an excellent example of both heat transfer and physical changes. Let's break it down:

Heat transfer:

When you microwave the bar of Ivory soap, heat is transferred from the microwave to the soap, causing the temperature of the soap to increase. This process involves heat transfer via electromagnetic waves known as microwaves, which can penetrate the soap and heat the water molecules within it. The water inside the soap absorbs the energy from the microwaves and turns into steam. This is an example of heat transfer, specifically through radiation.

Physical changes:

As the heat causes the water molecules in the soap to turn into steam, the gas expands and takes up more space. This expansion pushes the soap to puff up and create a fluffy, cloud-like structure. The process involves a physical change, as the water within the soap changes its state from liquid to gas (steam). However, the soap's molecular composition remains the same.

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In Conclusion

The exploding soap experiment is an exciting and educational activity that demonstrates the fascinating effects of heat transfer and gas expansion in a fun and visual way. By microwaving a bar of Ivory soap, children can witness the transformation of an ordinary household item into a cloud-like, expanded mass. This engaging experiment not only sparks curiosity in young minds but also teaches important scientific concepts related to heat, gas expansion, and physical changes. With adult supervision and proper safety precautions, the exploding soap experiment can be a fun and memorable experience for both parents and children. Moreover, finding creative ways to repurpose the expanded soap, like incorporating it into art projects or using it for handwashing or laundry soap, can add even more value to this intriguing science exploration.

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More Science Fun

Here are a few more easy and fun experiments that kids can do at home with their parents to learn about gas expansion, heat transfer, or physical changes:

Chocolate melting experiment:

Place different types of chocolate (dark, milk, and white) on separate plates and watch how they melt at different rates when exposed to the same heat source, like sunlight or a warm room. This yummy experiment showcases heat transfer and physical changes in matter (solid to liquid).

Ice cube race:

Set up an ice cube race on a flat surface by placing ice cubes on wax paper or aluminum foil. Use a hairdryer or fan to blow warm air on the ice cubes and watch as they slide across the surface, demonstrating heat transfer and physical changes (melting).

Sugar cube dissolving:

Fill three cups with water (hot, room temperature, and cold) and place a sugar cube in each cup. Watch to see which sugar cube dissolves the fastest, demonstrating the effects of heat transfer on the rate of a physical change.

Homemade thermometer:

picture for homemade thermometer kids science experiment

Fill a clear plastic bottle with colored water, add a straw, and seal the opening with clay or playdough. As the temperature changes, the water level in the straw will rise or fall, indicating the temperature change and showcasing heat transfer and gas expansion.

These fun science activities can help children learn more about gas expansion, heat transfer, and physical changes while enjoying hands-on activities with their parents.

Always ensure adult supervision and proper safety precautions during these experiments and HAVE FUN!

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