Spooky Halloween Balloon Science

These Halloween activities for kids are not only educational but also so much fun! Kids will love this simple chemistry experiment that involves a little bit of art, and a whole lot of spooky surprises! A great project for preschool to elementary using simple, easy to find materials.

Halloween Science and STEAM Project for Kids

Halloween Balloon Science Activity for Kids

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A few years ago we were stuck at home. The weather had been brutal for weeks and the kids were going stir crazy stuck at home, just doing their homeschool work. At the time it was early February, so I decided to try a Groundhog Day Activity as quick activity to break up our day.

And it was HUGE hit!

In fact the kids were recently talking about our Ground Hogs popping up activity and asking if we could do a Halloween version with ghosts and pumpkins.

Sounded like a brilliant idea to me!

So we gathered up our supplies and set out to do some Halloween Science!

The kids had so much fun as their Pumpkin heads and Ghostly faces would pop up! The best part was how easy, fun and fast this activity was. We even turned it into a race to see which ones would get the biggest, the fastest. It would make a fantastic Halloween Party Game.

Halloween Balloon Science


Empty plastic bottle (we used 1 litre pop bottles)
Balloons (Orange and White)
Baking Soda
Sharpie (Black)
Bag Clips


Clean up your bottle, we liked adding little sleeves made out of orange construction paper. You could have the kids decorate it to make their piece special and add more of a creative art component.

Blow up your balloon and close off the end with a bag clip to keep the air in. Take a Sharpie and draw your design. Make the designs as fancy as you wish! Once you are finished drawing your design, let it sit for a minute or two to dry before removing the clip.

Add vinegar to the bottle. This is easiest to do if you use a funnel. I added about 1 cup to my 1 litre bottle.

Place a small funnel inside the balloon and fill it with some baking soda. I used 1 heaping teaspoon.

Feel free to adjust these ratios to see how it affects your results. This makes for a fantastic scientific investigation!

Carefully slip the balloon over the mouth of the bottle. Ensure the balloon is on securely.

Time for a Spooky Reaction!

When you are ready to trigger the chemical reaction, simply lift up the balloon and shake so the baking soda falls into the bottle. The reaction will start and your balloon will start to inflate revealing your spooky creation!

Give the balloon a little shake to make sure all the baking soda falls down into the vinegar. See how big your Spooky Balloon gets!

Check out our Halloween experiment in action!

Halloween Science Lesson

This is one of our favourite simple chemistry reactions, making it perfect for young scientists. Our spooky balloon science is powered by the ever popular baking soda and vinegar reaction! We love this reaction because it involves two items everyone has in their home, making it easy, quick science for kids!

Baking Soda and Vinegar is a simple acid-base chemical reaction. Vinegar or Acetic Acid has the chemical formula CH3COOH . Baking soda is a base also known as Sodium Bicarbonate and has the chemical formula ‎NaHCO3 . During this reaction the products are sodium acetate ( C2H3NaO2 ). Sodium acetate is made of 1 sodium ion, 2 carbon atoms, 3 hydrogen atoms, and 2 oxygen atoms. The other products are water ( H2O) and carbon dioxide ( CO2 ) gas.

Carbon dioxide is the gas that causes the bubbling during the reaction. When those bubbles pop, the gas is released into the air where it tries to escape the bottle. That gas is what inflates the balloon, revealing our spooky Halloween surprises.

Take a feel of the bottle during the reaction. What does it feel like? The gas also makes the bottle firmer due to the increased pressure.

Here is the chemical formula of this reaction

C2H4O2 + NaHCO3 -> NaC2H3O2 + H2O + CO2
vinegar + sodium bicarbonate -> sodium acetate + water + carbon dioxide

This is a fantastic Halloween Science project for kids. If you are looking for more ideas, check out our 31 Days of Halloween STEM Activities resource! It’s packed full of ideas to celebrate the season.

Love Halloween? Love STEM? Celebrate the countdown to Halloween with our 31 Days of Halloween STEM Activities. A little Halloween STEM for every day!

Halloween Chemistry Experiment and STEAM Activity

More Halloween Activities for Kids

Halloween Skittles Experiment
3D Halloween Art Project for Kids