9 - Self-Inflating Balloon

This is a great experiment to introduce little ones to the wonderful world of chemistry. Using ingredients found in the home, this experiment demonstrates a simple chemical reaction resulting in a self-inflating balloon!

What you will need

  • 1 balloon
  • 50ml acetic acid (white vinegar) - about 4 tablespoons or 1/4 cup
  • 5g sodium bicarbonate (or bicarbonate of soda or baking powder) – about one level teaspoon
  • 1 small empty drinks bottle (approx. 500ml)
  • Funnel (or paper about 20cm x 15cm to make a cone)

How to do it

  • Use the funnel to pour the sodium bicarbonate into the balloon. 
  • Carefully pour the acetic acid into the bottle.
  • Put the neck of the balloon well over the neck of the bottle making sure the gas will not escape (this can be a bit tricky so perhaps ask an adult to help).
  • Lift the end of the balloon and shake the sodium bicarbonate from the balloon into the bottle.
  • Note the size of the balloon when the reaction is finished.
  • As an additional experiment, repeat the steps above but increase the acetic acid to 100ml and the sodium bicarbonate to 10g. What difference do you notice between the balloon’s size after the second experiment compared to the first one?

What is happening?

The balloon inflates due to a chemical reaction taking place inside the bottle. The chemical formula for acetic acid is C2H4O2 and the chemical formula for sodium bicarbonate is NaHCO3. When the two mix, the chemical equation for the reaction between vinegar and baking soda is C2H4O2 + NaHCO3 = NaC2H3O2 + H2O + CO2. In other words, acetic acid + sodium bicarbonate = sodium acetate + water + carbon dioxide (which inflates the balloon).

Share your experiment...

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All experiments must be conducted in the safest possible way. An adult must be present wherever it states one is required. Never do anything dangerous with chemicals or fire for your sake and those around you.