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20 Minute Labs: Boo! Exploding Bags

logo | Yellow Scope


It's almost Halloween! Are you carving pumpkins? Or dressing up like ghouls or ghosts? We have some fun science experiments to help put you in the Halloween spirit!

In this month's 20 Minute Lab, we put a twist on a classic chemical reaction to make exploding Halloween bags. This is a great project for a sunny or rainy day. (Bonus: the rain will help clean up your explosions!)

Note: The listed ingredients are enough for a single bag, so keep in mind that you'll need more of everything if you want to do more than one! Also, this is a messy experiment that is best done outdoors.


  • supplies | Yellow Scope
    Zip-seal baggie (sandwich size)
  • Permanent marker
  • Tablespoon measure
  • 3 tablespoons corn starch
  • 1 cup water
  • 1/2 - 3/4 cup vinegar
  • Food coloring
  • Toilet paper square
  • 2 tablespoons baking soda
  1. First, give your baggie a costume! Use your permanent marker to draw a fun face! We made a Frankenstein, a Jack-O-Lantern, and a ghost.
  2. Add the corn starch to the bag.
  3. Then add the water and vinegar.
  4. baggies | Yellow Scope
    Add some food coloring. Suggested food coloring:
    • Ghoul: 13 drops of green
    • Pumpkin: 2 drops of red, 10 drops of yellow (red is strong, so for a true orange go easy!)
    • Ghost: no food coloring needed!
  5. Seal up the bag tightly and shake it to thoroughly mix. Massage the bottom corners to break up the corn starch.
  6. baking soda packet | Yellow Scope
    Set the sealed bag aside.
  7. Now lay a square of toilet paper on the table and carefully add two tablespoons of baking soda to the center of the square. 
  8. Fold the corners of the toilet paper over the baking soda to make a packet. (If you're making enough for several experiments at one time, you can add a small piece of tape to hold the packets together!)
  9. Now place the sealed bag on the ground outside (or somewhere that can get messy!)
  10. Open the bag just a bit and slip the baking soda packet inside.
  11. Quickly seal the bag back up and step away.
  12. Observe what happens!



Did your baggie bubble up and explode? Why do you think this happened?

chemical reaction occurred between the vinegar and the baking soda. Baking soda is a base and vinegar is an acid.

ph scale | Yellow Scope

When you mixed them together, an acid-base reaction occurred.

In this chemical reaction, a new substance is formed - carbon dioxide (CO2)! CO2 is a gas, and as the reaction happened in your bag, more and more COgas was released (those were the bubbles you saw!) The pressure increased in the bag until it exploded!

soda exploding | Yellow Scope

The reaction would happen with the corn starch - but we added it here because it helps to thicken the mixture so you can better see the colors. We also added the extra to fill up space in the bag, so we didn't have to use too much vinegar and baking soda.

Have you ever shaken up a can of soda and watched it explode when you open it? That's similar to what's happening in this experiment! The carbon dioxide in the soda creates pressure in the can, that escapes when you open a hole in the top!

To find out more about acids and bases, check out our Acids, Bases, & pH kit!


Let us know how your experiments turned out! Share your photos and results with us on Facebook, Twitter, Instagram, or send us an email to We love getting your messages!

For more exciting experiments, check out our Yellow Scope science kits on the Shop tab of our website!

Chelsea Schuyler
Chelsea Schuyler