Fire mountains
Deep under the ground, rock can be so hot that it melts. Find out what a volcano is, what lava and ash are, and make your own fizzy model volcano.
Read
A volcano is an opening in the ground. Hot melted rock, ash and steam can come out of it.[2]
Deep under the ground, rock can get so hot that it melts. Melted rock under the ground is called magma. When it comes out of a volcano, we call it lava.[1][2]
Lava is very, very hot: much hotter than an oven. Glowing yellow lava is hotter than red lava.[7]
Some volcanoes let runny lava flow out slowly, like in Hawaii. Others explode and blow ash high into the sky.[1]
Ash from a volcano can fall back down like grey powdery snow.[1]
Some volcanoes erupt nearly all the time. Others sleep for hundreds of years.[8]
Try it: Fizzy model volcano
You need
- A small plastic bottle
- A tray with sides
- Sand or play dough to build a mountain around the bottle
- 2 spoons of baking soda
- A cup of vinegar
- A squirt of washing-up liquid
- Optional: a drop of red food colouring
Safety
Wear safety glasses. The teacher pours the vinegar. Do not taste anything. Wipe up spills so nobody slips, and wash hands afterwards.
What to do
- Stand the bottle in the tray and build a mountain of sand or dough around it. Leave the top open.
- Put 2 spoons of baking soda and a squirt of washing-up liquid into the bottle.
- Guess: what will happen when we add the vinegar?
- The teacher pours the vinegar into the bottle. Stand back and watch!
- Try again with only 1 spoon of baking soda. Is the 'eruption' bigger or smaller?
What happens, and why?
Baking soda and vinegar make lots of gas bubbles. The bubbles push the foam up and out, like gas pushes magma out of a real volcano. This is only a model: a real volcano has melted rock, not vinegar![1]
Play: Volcano or not?
Does it come out of a volcano? Tap the right group.
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Quiz
Other ages: Ages 10–11 · Ages 15–16