Make soap bubbles float!

Author: Maddie Van Beek

Have you ever blown soap bubbles before? When you blow a bubble, you are creating an air pocket surrounded by a layer of soap. Even though the bubble is filled with air, the surrounding soap is heavier than the air around the bubble. Because of the added weight, the bubbles fall to the ground and POP. Today, you are going to make bubbles float in the air! How will you do this? Let’s find out! 

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Think back to other experiments; we have learned about carbon dioxide in several past blog posts, such as when you combined baking soda and vinegar to blow up a balloon or when you used an Alka-Seltzer tablet and water to set off film canister rockets. If you missed these experiments, check them out below! 

Use vinegar and baking soda to blow up a balloon

Make your own film canister rocket

In those activities, you created carbon dioxide gas through a chemical reaction. Today, you are going to combine baking soda and vinegar to create carbon dioxide gas. When you combine baking soda (a base) and vinegar (an acid), you are creating an acid-base reaction. This reaction then produces carbon dioxide. What does this have to do with making bubbles float? 



Carbon dioxide and oxygen are both gases, but some gases are denser than others. Carbon dioxide is denser than air. Click on the button below to learn more about why carbon dioxide is denser than oxygen. 

Why is carbon dioxide heavier than oxygen?

Because carbon dioxide is denser than the air inside the soap bubble, soap bubbles that land on the surface of the invisible carbon dioxide will stay afloat. Let’s try it out! 



YOU WILL NEED:

• Soap bubble solution with a bubble wand
• Aquarium or other large transparent container
• Baking soda
• Vinegar
• Shallow pan or bowl that will fit inside the larger container

Here’s a video of what you are about to experience! In this experiment, the participants used dry ice instead of baking soda and vinegar. As you know, baking soda and vinegar gives off carbon dioxide, which is what will make your bubbles float. Dry ice is frozen carbon dioxide. When the dry ice melts, it turns straight from a solid into a carbon dioxide gas. 

Here’s what to do!

1. Dip the bubble wand into the bubble solution and blow bubbles. Observe. What happens when you blow the bubbles? How long does it take for them to fall to the ground? 
2. Set the large transparent container on a table or countertop where you can easily observe from the side. 
3. Measure 1/2 cup of baking soda and dump it into the smaller container. 
4. Place the smaller container in the center of the larger container. 
5. Measure 1 cup of vinegar and pour it into the smaller container of baking soda. What happens? Write down observations in your observation notebook. You should have seen the vinegar and baking soda fizz and bubble. You have just created an acid-base reaction!

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6. Wait about a minute for the fizzing to slow down. Then use your bubble wand and bubble solution to gently blow bubbles into the large container. It may take a few tries to get the bubbles to land in the container. 


7. What happens when the bubbles fall into the container? Record your observations. 


8. Try timing your bubbles! How long do they float? Does using different amounts of vinegar or baking soda make a difference? Test it out! 



References

http://scifun.chem.wisc.edu/homeexpts/SOAPBUBL.html

http://www.hometrainingtools.com/a/bubbles-and-baking-soda

https://www.youtube.com/watch?v=Tr72CHwpdH4

http://discoveryexpress.weebly.com/homeblog/whats-heavier-carbon-dioxide-or-oxygen