What You Need
- 850g plain flour
- 320g salt
- 480ml water
- 4 tablespoons of cooking oil
- an empty half litre plastic drinks bottle
- oven dish
- food colouring (optional)
- washing up liquid
- two tablespoons of bicarbonate of soda
- vinegar
What To Do
- In a large bowl, mix together the flour, salt, water and oil until smooth and firm (you can add more flour or water to get the right consistency)
- Place the drinks bottle in the oven dish and mould the dough around it (leaving the top clear) to make your volcano
- Unscrew the lid of the bottle and fill it almost full with warm water
- Next add a little red food colouring, 6 drops of washing up liquid and two tablespoons of bicarbonate of soda
- Slowly pour the vinegar in and watch as 'lava' comes spewing out the top of your volcano
The Science Bit
The bicarbonate of soda (alkali) reacts with the vinegar (acid) and releases carbon dioxide (a gas). The carbon dioxide escapes out the top of the bottle (just like when you shake up a fizzy drink and open it) but the gas molecules are trapped in the washing up liquid forming