Pop Top Fountain

Create an explosive fountain of foam and carbon dioxide gas by mixing sodium bicarbonate and vinegar. Watch out! This experiment is messy.

Australian Curriculum links

  • Science > Chemical Sciences > Year 5 > ACSSU077
  • Science > Chemical Sciences > Year 6 > ACSSU095
  • Science > Chemical Sciences > Year 9 > ACSSU179

You'll need

  • empty drink bottle with pop-top lid
  • vinegar
  • detergent
  • sodium bicarbonate
  • teaspoon

Try this

  1. Close the pop-top and unscrew the lid from the drink bottle.
  2. Pour some vinegar into the bottle and add a small squirt of detergent.
  3. Add a teaspoon of bicarbonate of soda to the drink bottle.
  4. Quickly screw on the lid, shake the bottle and place it on a flat surface.
  5. Stand back and, within a few seconds, a foamy fountain will shoot out of the bottle.

What's happening?

When sodium bicarbonate is mixed with vinegar, it produces a lot of carbon dioxide gas. When detergent is added, the gas bubbles away and creates lots of foam. The gas builds up pressure inside the container until eventually it pushes open the pop-top to create a spectacular column of white foam.

The chemical reaction between sodium bicarbonate and vinegar is an example of an acid-carbonate reaction. The acetic acid in the vinegar reacts with the sodium bicarbonate to produce sodium acetate (a type of salt) and carbonic acid. The carbonic acid is unstable and continues to break down into carbon dioxide gas and water.

Real world links

Sodium bicarbonate is used in some fire extinguishers, known as ‘dry chemical fire extinguishers’, which are good for putting out small kitchen fires and electrical fires. Carbon dioxide is used in gas fire extinguishers which are designed for putting out electrical fires.