An exploding volcano is a geologic process that can be reproduced on a small scale as a science activity. Engaging young students in this types of experiment can lay a solid foundation for improving science literacy and future research in the Earth sciences. These activities can also be useful for student science fairs. As with all science experiments, adult supervision is strongly recommended.
How to Make an Exploding Volcano
Increased activity at Mt. Redoubt Volcano, Alaska, has renewed interest and curiosity about how volcanoes work. This experiment is appropriate for students of all ages and is especially useful for students that require a more simple activity. The materials you will need are:
- Salt dough (six cups flour, two cups salt, four tablespoons vegetable oil, and two cups of water)
- Two-liter plastic soda bottle
- Baking sheet
- 1.5 liters of warm water
- Red food coloring
- Six drops of liquid dish detergent
- Two tablespoons of baking soda
- Vinegar
Mix the ingredients for the salt dough until the dough is smooth and firm, adding more water if it is too dry. Next, stand the plastic soda bottle right-side up in the middle of the baking sheet and sculpt a volcano around it using the dough. Remember to leave the bottle opening clear - this is the crater of your volcano and from where the lava will flow. Once the dough is dry, you can paint it brown our black to make it look like a volcano. Add any extra features you like, for example, valleys coming down the volcano's flanks.
Mix the warm water with the red food coloring to give it the appearance of red lava. Pour the warm water mixture carefully into the bottle opening so that the bottle is about three-quarters full. Add the six drops of liquid dish detergent and then the baking soda to the water in the bottle. Now comes the fun part - slowly pour the vinegar into the bottle opening. This vinegar should chemically react with the water mixture and a red foam will erupt from your volcano. The chemical reaction produces carbon dioxide, which is one of the gases that causes volcanoes to erupt.
Magmatic Gases Cause Explosive Eruptions
Explain to your student that it is the presence of gases, such as carbon dioxide, sulfur dioxide and water vapor, that causes magma to be erupted from a volcano. Magma with less gas, such as the magma under Hawaiian volcanoes, erupt less explosively. Magma with more gas, such as the magma under Mt. Redoubt volcano, will cause more explosive eruptions.
Not only do these gases cause explosive eruptions, but in high amounts they can alter the climate. The three most prominent gases emitted through volcanic eruptions - water vapor, carbon dioxide and sulfur dioxide - are also greenhouse gases. Historical large volcanic eruptions have been known to change the global climate. For example, the 1991 eruption of Mt. Pinatubo in the Philippines spewed so much greenhouse gas that global temperatures were warmer in the summer and cooler in the winter for almost two years after the eruption.
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Sources:
McCormick, A.P.L., W. Thomason, and C.R. Trepte (1995), Atmospheric effects of Mt. Pinatubo eruption, Nature, 373, 399-404.
Alexandra Matiella Novak - With a PhD in Geology and expertise in science education, Alexandra is passionate about increasing the public's Earth science literacy.
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