Materials Required
- Balloon
- Empty plastic bottle
- Vinegar (1 cup)
- Baking soda (⅓ cup)
- Funnel
Instructions
- Using a funnel, carefully put baking soda into the balloon. You'll need about ⅓ cup of baking soda.
- Pour 1 cup of vinegar into the empty bottle. The ratio of baking soda to vinegar should be about 1:3.
- Carefully stretch the opening of the balloon over the mouth of the bottle. Important: Keep the balloon hanging to the side so the baking soda doesn't fall into the bottle yet.
- Once the balloon is securely attached to the bottle, lift the balloon upright so the baking soda falls into the vinegar.
- Watch what happens to the balloon!
Safety Note: Do this experiment over a sink or tray in case of spills.
What's Happening?
Baking soda (sodium bicarbonate) and vinegar (acetic acid) react together to create three products:
- Carbon dioxide gas (CO₂)
- Water (H₂O)
- Sodium acetate (a salt)
The Chemical Reaction:
NaHCO₃ + CH₃COOH → CH₃COONa + CO₂ + H₂O
Where:
- NaHCO₃ = Baking soda (Sodium bicarbonate)
- CH₃COOH = Vinegar (Acetic acid)
- CH₃COONa = Sodium acetate
- CO₂ = Carbon dioxide
- H₂O = Water
The carbon dioxide gas has nowhere to go, so it rises up into the balloon and inflates it! This is the same type of gas that makes sodas fizzy and is what we breathe out.
Extra Activity: CO₂ Density Test
Carbon dioxide is heavier (more dense) than regular air. You can test this:
- Inflate two balloons to the same size - one with CO₂ from this experiment, and one with air from your mouth.
- Drop both balloons from the same height at the same time.
- The CO₂-filled balloon should fall faster and reach the floor first!
This happens because CO₂ is denser than air, so gravity pulls it down more strongly.