Activity

Fizz-Inflator Challenge

A chemical reaction inflates a balloon without using your mouth. Baking soda, vinegar, and a competitive streak.

Ages: 7–11
Duration: 45 minutes

What kids build

A balloon inflated by CO2 from a real acid-base reaction, with a measurement of whose team's balloon got biggest.

Materials we bring

Empty plastic water bottle (16 to 20 oz)
Balloon, pre-stretched
Baking soda, 2 to 3 tablespoons per team
Vinegar, about half a cup per team
Small funnel or rolled paper

How we run it

01 Set up tables with materials for each team.
02 Place a tray or baking sheet under each team's workspace to catch spills.
03 Tell kids they are chemists today and their mission is to inflate a balloon with a chemical reaction, no lungs allowed. Biggest balloon wins.
04 Use the funnel to pour vinegar into the water bottle until it is about one third full, roughly half a cup. Place the bottle on the tray so it cannot tip over.
05 Stretch out your balloon by blowing it up a few times and letting the air out. That makes it easier to inflate during the reaction. Decorate with markers, a face, a team name, or patterns.
06 Use the funnel to spoon 2 to 3 tablespoons of baking soda into the balloon. Be careful not to spill.
07 Carefully stretch the opening of the balloon over the mouth of the water bottle. Keep the balloon hanging to the side so the baking soda does not fall into the vinegar yet. Check that the balloon is securely attached with no gaps or air leaks.
08 On the count of three, lift the balloon so all the baking soda drops into the vinegar below. Watch the bubbles and fizz begin. The balloon inflates as carbon dioxide gas fills it.
09 Watch the reaction carefully. What do you see? What do you hear?
10 Once the reaction stops and bubbles settle, wrap a measuring tape around the widest part of the balloon to measure circumference, or compare by sight.
11 Write down your results in the data table.
12 Compare teams. Whose balloon got biggest? What did they do differently?

Kids pour vinegar into a bottle, funnel baking soda into a balloon, stretch the balloon over the bottle mouth, and dump the baking soda in. The reaction produces carbon dioxide gas which inflates the balloon. Teams compete to produce the biggest balloon. The best ones measure, observe, and iterate.

Real-world connection

From soda fizz to bread rising

The same acid-base reaction kids run in this activity is what makes bread dough rise, what gives soda its fizz, and what powers some classroom fire extinguishers. The chemistry scales from a water bottle all the way up to industrial food production.

Go deeper

Extension ideas

Temperature test

Try warm vinegar versus cold vinegar. Which makes a bigger balloon, and why do you think that is? (Hint, temperature speeds up reactions.)

Ratio test

What happens if you double the baking soda but keep the vinegar the same? What about the reverse? Kids can learn that chemical reactions have a limiting reactant.

When we have run this

Scheduled and past visits

Past

APR 2 2026

Thursday, April 2
Completed

Sewell Mill Library and Cultural Center

Kids used baking soda and vinegar to create a chemical reaction that inflated a balloon on top of a water bottle with no mouth required. Teams competed to see whose balloon got biggest while learning about acids, bases, carbon dioxide gas, and pressure.

Bring this to your space

Want the Fizz-Inflator Challenge at your library or school?

Tell us your space, your age range, and rough timing. We will come to you. Materials are on us.

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