Materials:

2 tall cups

Water

Bicarbonate of soda

Washing-up liquid

Vinegar

Parental supervision advised.

Instructions:

1. Pour water into cup until it’s about a third full.
2. Add two spoonfuls of bicarbonate of soda.
3. Fill a separate cup with vinegar and a squirt of washing-up liquid. Mix well.
4. Quickly pour the vinegar mixture into the cup of water.
5. Stand back and watch the eruption!
6. Add more vinegar to repeat the reaction until the bicarbonate of soda mixture is gone.

How It Works

When they come into contact, vinegar and bicarbonate of soda react and form a gas called carbon dioxide (CO₂). The carbon dioxide gas surges upward through the mixture, causing it to foam up and expand out of the cup. Awesome!

Time to Experiment

Repeat the process a few times, but with small differences each time. Record your findings so that you can remember the best way to achieve maximum blast!

  Skip the washing-up liquid. Is there a difference?

  Try adding one spoonful fewer of bicarbonate of soda. What happens?

  What if you added the washing-up liquid to the bicarbonate of soda mixture instead?

  What other variations can you think of? Try them all!