Erupting volcano
A little bottle hidden in a sand mountain, vinegar, bicarbonate… and red lava that foams and overflows.
Age : age 4+
Materials
- A small plastic bottle (330 ml)
- A big basin or roasting tin : The volcano overflows!
- Sand, soil or salt dough : To build the mountain.
- 1 glass of white vinegar
- 2 tablespoons of bicarbonate of soda
- Red food colouring or grenadine syrup : For the lava colour.
- A little washing-up liquid : Optional: more foam.
Steps
Build
- Stand the bottle in the middle of the basin.
- Build a mountain of damp sand all around it, leaving the neck clear.
- Pour the vinegar, the colouring and a drop of washing-up liquid into the bottle.
The eruption
- Everyone takes a step back.
- Tip the bicarbonate into the neck in one go (a paper funnel helps).
- Watch the lava foam and flow down the slopes.
- Try again with different amounts: more bicarbonate, bigger eruption?
Vinegar and bicarbonate react together and make a gas, carbon dioxide. This gas takes up a lot of room: it pushes the liquid out of the bottle. In a real volcano, gases also push the magma upwards.
Do it outside, and compare the eruption with cold vinegar and warm vinegar.
If it goes wrong
- Hardly any foam : More bicarbonate, fresh vinegar.
- Just bubbles at the bottom : Tip it all in at once.
- Sand collapses : Dampen it so it holds.
Safety
- Don't lean over the neck during the eruption, and never put a lid on.
- Vinegar stings eyes: wash hands afterwards.