What you need:

• sodium bicarbonate (baking soda)
• white vinegar
• washing-up detergent
• an empty pop top drink bottle

What to do:

1. Close the pop-top and unscrew the lid from the bottle.
2. Pour some vinegar into the bottle and a small squirt of detergent.
3. Add a teaspoon of sodium bicarbonate to the bottle.
4. Quickly screw on the lid, shake the bottle and place it on a flat surface.
5. Stand back!

Safety note:

This experiment is messy and probably should be done outside. You might want to wear safety eyewear when shaking up the bottle. It might also be good to wear a raincoat.

What’s happening?

This is the same kind of chemical reaction as in the sherbet activity. In this case the reaction can happen much more quickly because there is already water present in the vinegar and the chemicals can mix almost instantly.

acid + carbonate –> carbon dioxide + salt + water
C₂H₄O₂ + NaHCO₃ –> CO₂ + NaC₂H₃O₂ + H₂O

The detergent just makes it more fun with lots of foam and mess being created by the carbon dioxide bubbles. The pressure rapidly builds in the bottle and pops the lid open, spraying foam high into the air.