Explosive Science: Volcano Experiment Using Acids & Bases

Build a volcano with the kids, and watch as they erupt in smiles! This experiment is fun and educational. You can spend some quality time with your kids while teaching them about science. There are arts and crafts involved in building your volcano, and even more fun destroying it with a harmless (yet thrilling) eruption of bubbles.

What You’ll Need

  • 2 tbsp. baking soda (make sure you do NOT use baking powder)
  • ¼ cup vinegar
  • A container for the reaction (a soda bottle with the top cut off works very well, but you can use anything that’s waterproof, has an open top, and strong sides) -- Or use a pocket volcano by Science on Your Palm
  • Dish soap
  • Food coloring (red and yellow)
  • Cleaning supplies (things might get messy)

Building a Basic Volcano

To get a basic eruptions going, chose a strong and sturdy container for the experiment. The easiest way to go about the container is to simply cut the top off a 2-liter bottle.

Place your container in the middle of a table (or somewhere you won’t mind a mess). Pour ¼ cup of vinegar into the container (use more for a larger container, and a larger reaction – up to one cup).

Add a spoonful of dish soap (and food coloring make it look more like lava). When you’re ready, add the baking soda, and stand clear. (The moment you add the baking soda, the eruption will begin!)

Immediately, you will see an eruption of bubbles come out the top of your volcano, just like lava. (Don’t worry, it’s not an explosion, it’s more of a bubbling reaction that will continue for a few minutes.)

For Extra Credit

Make a realistic-looking volcano. It takes some craft skills but it will make your vinegar and baking soda eruptions will look even more impressive!

You can make your volcano outside, using natural materials you find, or out of paper mâché or clay. Paint your volcano and add decorations, like broccoli trees or action figures to complete a realistic look.

To help with the mess, place your volcano in a container (an old pizza box works perfectly.) Then you can also decorate this container by adding background drawings of a town, or lakes, streams, roads, etc. on the interior section of the box’s lid.

The best part of this experiment is making the volcano with your kids and watching the eruption when lava comes cascading down, through the trees, and to the town below. Plus, building the volcano will allow you to explain the science and geology behind a volcano when you do the experiment.

The Science Behind the Magic

The eruption of bubbles comes from a reaction between the vinegar and baking soda. The baking soda (sodium bicarbonate) is a base while the vinegar (acetic acid) is an acid. Every liquid will be somewhere on the scale of acid or base; this scale is called the PH scale.

The PH scale goes from 1-14, with 7 being neutral (this is why we use them in our pools, to achieve a neutral PH). An acid has a low PH (0-6), while a base has a high PH (8-14).

Before the experiment you can show your kids the PH scale by using a pool meter to test your ingredients. The vinegar should have a PH of around 2, while the baking soda should have a PH of around 9.

When chemicals that have an opposite charge are combined, they react together to neutralize and balance each other out. This is called a chemical reaction, and it’s what causes the physical reaction in your eruption.

When these particular acids and bases are mixed, they break down and form into new chemicals: water, salt, and carbon dioxide (Don’t worry, carbon dioxide is the stuff you breathe out, and the stuff that makes your soda fizz – it’s completely harmless in these small doses).

When the carbon dioxide is created through the reaction, it builds up pressure in the enclosure. Since the gas takes up more space than the liquid, the pressure builds up until it has to escape. So, if you want a bigger eruption, simply make a smaller opening to your container.

Take It Further

This experiment lends itself well to what actually happens in real volcanoes.

Volcanoes are generally found where the Earth’s plate tectonics meet. These plates cover the Earth, and move very slowly over millions of years.

These slow-moving plates are what caused land masses to transform from Pangaea to the continents we know today. Show your kids a map of the world, and describe how the plates used to be together, and how over the years, they have moved apart. Then show them how the continents still look like puzzle pieces that fit together.

When these plates move apart from each other, they cause openings, which allow the lava, ash, and gases from below the surface to escape. Lava is molten rock (or magma) heated up by the Earth’s core.

When it reaches the surface, the lava cools, changing it from a liquid to a solid. In this chemical reaction, carbon dioxide is released, and the pressure causes the same kind of eruption in the experiment.

But with real volcanoes, when the lava cools, it turns back into rock. This is how the islands of Hawaii were formed, and are still being formed to this day. Each island was once an underwater volcano that erupted, and the molten rock cooled into a land mass.

Pretty cool, huh?

What are some of your favorite science experiments that use simple household ingredients?

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