Here is a recipe for creating an erupting volcano:
1 large bottle large baking pan 1 TB flour 1 TB baking soda 20 drops red food coloring
Put the bottle in the pan. Pour the flour, baking soda and food coloring inside the bottle.
1 cup vinegar
Pour 1/2 cup of vinegar into the bottle. Watch it explode! When the bubbles die down, pour the rest of the vinegar in to make it erupt again.
And then you can talk a little bit about science… “The baking soda reacts with the vinegar, producing carbon dioxide gas. As the gas forms, it expands quickly, pushing the liquid and the flour particles out the top of the bottle. The mixture of the gas, flour, red food coloring, and liquid produces the foam, which simulates the foamy magma in an active volcanic eruption.” p.21
From Janice VanCleave’s Volcanoes: Mind-boggling experiments you can turn into science fair projects.
There I am in front of a real volcano twelve years ago in Guatemala.