What You Need:
- Adult helper • Aluminum foil • A whole pumpkin
• Baking soda, ¼ cup • Tray • Dish soap • Marker • Food coloring
• Cutting board • Vinegar, 1 cup • Knife - Measuring cup • Spoon
What You Do:
Step 1: Have your adult helper cut off the top of your pumpkin. Use the spoon to remove all the pulp and seeds.
Step 2: Draw a face on the pumpkin.
Step 3: Have your adult helper use the knife to cut out the face you drew.
Step 4: Place the jack-o’-lantern on a tray. Place a piece of aluminum foil in the center of the jack-o’-lantern to create a wall. This helps keep the foamy reaction near the jack-o’-lantern’s mouth.
Step 5: Fill the measuring cup with about ¼ cup of baking soda. Add 6 to 7 drops of food coloring, and 3 drops of dish soap. Mix with the spoon.
Step 6: Place the cup inside the jack-o’-lantern, in front of the aluminum foil wall. Tilt the cup slightly toward the mouth opening.
Step 7: Pour ½ cup of vinegar into the cup. What happens?
Step 8: Add more vinegar to any leftover baking soda to continue the reaction.
What’s Going On:
A chemical reaction occurs between the baking soda, which is a base, and the vinegar, which is an acid. This acid-base reaction produces carbon dioxide gas — the same kind of gas we breathe out. The dish soap traps the gas in bubbles. Eventually, the pressure builds, and the bubbles overflow, forcing the foamy mixture out of the cup.
Placing this reaction inside a hollowed-out pumpkin creates a spooky, oozing effect!
Now Try This:
Experiment with different ratios of vinegar, baking soda, and dish soap. Does using more baking soda produce more foam? What happens if you add more soap?
Mad Science of Austin is a leading science enrichment provider. We deliver unique, hands-on science experiences for kids through after-school programs, birthday parties, workshops, special events, and summer camps. Our innovative programs are as entertaining as they are educational.
