Modelling an erupting volcano
This experiment will allow you to model the effect of lava flows using a safe chemical reaction and some simple materials. Obviously we do not want you to end up with real disasters in your own kitchen. This is quite a messy experiment so maybe it is best to do the actual final steps outdoors or in the bathroom in the bath/shower.
You will need:
For the volcano shape:
- 6 cups flour
- 2 cups salt
- 4 table spoons cooking oil
- 2 cups water.
- Small plastic bottle (soft drink bottle) with cap
- Cardboard sheet
- Baking tray or box with edges
- Some glue
For the lava:
- Red (and yellow) food colouring
- Few drops liquid detergent (dishwashing liquid)
- 1 cup water
- 1 tablespoon baking soda
- 1/4 cup vinegar
- Small piece of tissue paper
And last but not least ... a helping hand from an adult.
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Method
The small plastic bottle is the container for the (safe) chemical reaction which will produce the lava flow. However in order for the volcano to be realistic you can make the form of a volcanic mountain, using home-made clay – salt dough. You can use modelling clay or even paper mache (newspapers soaked in white glue and water or flour and water) covered with a waterproof varnish to allow you to re-use the model and make it lighter to carry around. Decide which outer covering you prefer. In the following method salt dough will be used.
First, glue the small plastic bottle to the cardboard sheet and fit this sheet inside the baking tray with upturned edges.
Now make the dough by mixing all the first 4 ingredients to a malleable dough in a big bowl – add a bit more water if you think it is necessary.
Build the “mountain” around the bottle top - you can decide to cut the bottle top off to leave a bigger opening which will be a bit more realistic. Make sure you seal ( if need be with glue) the upper edge of the dough to the bottle well so that the lava will not fall down in between them.
Let this dry and paint it as you like, add sand or soil with some glue to make your model volcano more life like.
NOW FOR THE ERUPTION
Add the water, vinegar, washing liquid and food colouring together into the bottle and stir with a straw.
Put the baking soda into a small piece of tissue, scrunch it up and drop it into the volcano which will now erupt.
You can experiment further with this: the 2 main ingredients causing the eruption are the vinegar and baking soda, so you can make a smaller opening, dissolve the baking soda (and other ingredients) in water and pour it in, then inject the vinegar rapidly with a syringe and move back fast – this might give a more explosive picture since the smaller opening should cause the liquid to escape faster and maybe spurt a little into the air.