Baking Soda Balloon Experiment
Vinegar and baking soda fizz inside a bottle and inflate a balloon on top without anyone blowing into it.
By WonderCraft Kids Editorial Team, Editorial team · Updated 5 September 2026
This is the classic fizzing reaction with a visible payoff: the gas produced actually inflates a balloon, so children can see the reaction working rather than just watching bubbles in a jar. It takes two minutes to set up and the reaction itself is over in under a minute, so plan on repeating it two or three times before interest fades.
What you need
- An empty plastic bottle
- White vinegar
- Bicarbonate of soda (baking soda)
- A balloon
- A small funnel
- A tray to catch drips
Step by step
- 1
Pour about 100ml of vinegar into the bottle.
- 2
Use the funnel to load two tablespoons of baking soda into the balloon.
- 3
Carefully stretch the balloon opening over the bottle neck without letting the soda fall in yet.
- 4
Once secure, lift the balloon upright so the soda tips into the vinegar.
- 5
Watch the balloon inflate as the reaction fizzes inside the bottle.
- 6
Repeat with different amounts of soda to compare how full the balloon gets.
What kids learn
Chemical reactions
Watching an acid and a base react gives children a chance to see gas produced from two liquids and powders that started with no gas at all.
Cause and effect testing
Changing the amount of soda and comparing results can help children practise simple fair testing.
Prediction
Guessing how big the balloon will get before running the reaction encourages children to make and check predictions.
Make it easier
Do the pouring together and focus on watching and describing the fizzing and inflating.
Make it more challenging
Test different vinegar amounts or bottle sizes and record which combination inflates the balloon most.
Safety and supervision
- Use only bicarbonate of soda and vinegar together; never mix with any other cleaning products.
- Keep quantities child-sized and do the pouring under adult supervision.
- The bottle may spray a little vinegar when the balloon is fitted, so work over a tray.
- Balloons can snap or burst, and broken pieces are a choking hazard; collect and discard every fragment immediately.
- Use a latex-free balloon if anyone taking part has a latex allergy.
Adult supervision is required for every activity on this site. Read our full child safety guidelines.
Pin this activity
A 2:3 vertical graphic, sized 1000×1500 for Pinterest. Save it for later or share it with another parent.
wondercraftkids.com
Baking Soda Balloon Experiment
Ages 4-8 · 10 min · low mess
Ages 4+ · Low mess
Suggested pin description
Baking Soda Balloon Experiment: Vinegar and baking soda fizz inside a bottle and inflate a balloon on top without anyone blowing into it. Ages 4+, 15 minutes total, low mess. Full step-by-step instructions and a materials list at WonderCraft Kids.
Free download
Get the FREE 20 Screen-Free Activities Pack
Twenty printable activity cards for ages 2–8, sorted by time and mess level. One email, no spam, unsubscribe any time.
Frequently asked questions
Why did my balloon not inflate much?+
Check the balloon seal is airtight against the bottle neck, and make sure the soda actually falls into the vinegar rather than sticking to the balloon.
Is the gas produced safe to breathe?+
Yes, the reaction produces carbon dioxide, the same gas found in fizzy drinks, so normal room ventilation is fine.
