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How to Make a Salt-Dough Volcano

Updated on December 15, 2016

Baking Soda Volcanos

Making an erupting volcano is a classic science experiment for young children. This project can be created for a science fair, as part of an earth science unit, or as part of a chemistry unit. The volcano's body is made from salt dough, which is inexpensive. The volcano can be baked and sealed with an acrylic sealer if it is intended for long-term use. There is no need to bake the dough if the volcano is made for a one-time demonstration. For use in a science project, consider painting the volcano - use acrylic paints, as tempera paints will begin to peel from the surface of the salt dough over time.

Other equipment required for the project include:

  1. A glass jar
  2. Baking dish (optional)
  3. Food coloring (optional)
  4. Acrylic sealer (optional)
  5. A deep dish for eruptions

Ingredients

  • 6 cups flour
  • 3 cups salt
  • 3 cups water
  • 2 tbs baking soda
  • Few drops liquid dish washing detergent
  • 1/2 cup vinegar

Salt Dough Ingredients

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6 cups of flour, 3 cups of salt, and 3 cups of water make enough salt dough for a small volcano.Mix the dough until it is smooth.Mold the dough around a glass jar.Bake the volcano at 225 degrees F until it is dry. This will take 4-8 hours.Paint (with acrylic paint), seal the volcano, and enjoy some baking soda and vinegar eruptions!
6 cups of flour, 3 cups of salt, and 3 cups of water make enough salt dough for a small volcano.
6 cups of flour, 3 cups of salt, and 3 cups of water make enough salt dough for a small volcano. | Source
Mix the dough until it is smooth.
Mix the dough until it is smooth. | Source
Mold the dough around a glass jar.
Mold the dough around a glass jar. | Source
Bake the volcano at 225 degrees F until it is dry. This will take 4-8 hours.
Bake the volcano at 225 degrees F until it is dry. This will take 4-8 hours. | Source
Paint (with acrylic paint), seal the volcano, and enjoy some baking soda and vinegar eruptions!
Paint (with acrylic paint), seal the volcano, and enjoy some baking soda and vinegar eruptions! | Source

Instructions

  1. Mix the flour, salt, and water in a large mixing bowl to form a smooth dough.
  2. Place the dough in a baking dish, and mold the dough into a volcano shape around a glass jar.
  3. If desired, bake the volcano at 225 degrees Fahrenheit until the dough is dry. This may take 4-6 hours. Baking the volcano will allow it to last longer.
  4. Paint the volcano and apply an acrylic sealer. Acrylic sealer is available at most craft stores and is easy to spray onto the finished volcano. Allow the paint and sealer to dry. This step is optional, but recommended if the volcano is meant to last for more than a single day.
  5. Place a few drops of liquid dish washing detergent into the glass jar. Add 2 tablespoons of baking soda. A few drops of red food coloring may also be added, if desired (this will make the eruption take on the color of the food coloring).
  6. To make the volcano erupt, pour in some vinegar (about 1/2 cup) and watch the "lava" flow!

Volcano Science Project

Make a volcano out of salt dough, add baking soda and vinegar, and watch the eruption occur!
Make a volcano out of salt dough, add baking soda and vinegar, and watch the eruption occur! | Source

What Makes the Volcano Erupt?

This "eruption" is a chemical reaction between the baking soda (sodium bicarbonate) and the vinegar (acetic acid). There are two reactions that take place to create the bubbling foam that flows.

The first reaction is a double replacement reaction. The sodium carbonate reacts with the acetic acid to form carbonic acid.

First, the baking soda exists in the following state:

NaHCO3 <-> Na+ + HCO3

The acetic acid exists as:

CH3COOH <-> H+ + CH3COO-

When the baking soda and acetic acid are combined, the following reaction takes place to form carbonic acid ( H2CO3):

H+ + HCO3 <-> H2CO3

The second reaction that takes place is a decomposition reaction. The carbonic acid is unstable and quickly decomposes into water and carbon dioxide (a gas). The formation of the carbon dioxide gas (CO2) is what creates the foam pouring out of the volcano.

Soda and Mentos: An Alternative Reaction

For a more explosive volcano, make a salt dough volcano and mold it around a plastic soda bottle. Do not bake the volcano with the plastic bottle in place - simply use an uncured version of the dough. If desired, allow the salt dough to air dry - this will take several days in a dry, warm location.

Add soda to the bottle - diet soda is the best, as it won't create a sticky, sugary mess. Place the volcano on a table outside, and drop the Mentos candies into the bottle. A fountain of foam will quickly shoot into the air. This "eruption" is extremely impressive - and messy! Do not perform this experiment indoors, as the jet of foaming soda will make a huge mess.

This reaction occurs because the chalky surface of the Mentos candy is filled with tiny holes. This allows a physical reaction to occur (as opposed to a chemical reaction). The carbon dioxide in the soda fills the microscopic holes in the candy and begins to expand rapidly. This is a process called nucleation.

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    • leahlefler profile image
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      Leah Lefler 4 years ago from Western New York

      Thanks, Writer Fox! We do a lot of projects over the summer, and the kids LOVE it!

    • Writer Fox profile image

      Writer Fox 4 years ago from the wadi near the little river

      What a great science project for little ones. Loved your video!

    • leahlefler profile image
      Author

      Leah Lefler 4 years ago from Western New York

      They are fun - everyone should do this at least once in their lives, Lipnancy!

    • Lipnancy profile image

      Nancy Yager 4 years ago from Hamburg, New York

      This looks like awesome fun. I never made one of those.

    • leahlefler profile image
      Author

      Leah Lefler 4 years ago from Western New York

      We had a lot of fun with it, randomcreative. You can speed up the process by not cooking the salt dough - you can use it in "raw" form and just toss the volcano when you're done with it.

    • randomcreative profile image

      Rose Clearfield 4 years ago from Milwaukee, Wisconsin

      How fun! I had no idea that you could do this with salt dough. Thanks for the great tutorial.

    • leahlefler profile image
      Author

      Leah Lefler 4 years ago from Western New York

      It is a classic science experiment for kids - my boys hadn't done this experiment before and they loved making the volcano "erupt" over and over again. I am going to try to do the soda and Mentos version this summer, Mhatter99, when I can keep it outside!

    • Mhatter99 profile image

      Martin Kloess 4 years ago from San Francisco

      Thank you for the memories. We are no stranger to our friend "the volcano".

    • leahlefler profile image
      Author

      Leah Lefler 4 years ago from Western New York

      They really had a great time with it. There is baking soda and foam all over the table, RTalloni!

    • RTalloni profile image

      RTalloni 4 years ago from the short journey

      Fun stuff! Thanks for this tutorial. Love those boys' smiles. :)

    • leahlefler profile image
      Author

      Leah Lefler 4 years ago from Western New York

      I was always stronger with English and the Biological Sciences than with math. I really had to work hard at the higher math concepts. I don't believe there are any "childish" experiments - a lot of theoretical science is accessible to everyone, because you don't need an understanding of quantum physics to get the general gist behind the ideas.

      Many of the great scientists of old based their theories on experiments, and the mathematical basis wasn't determined until a later point in time. Basic ideas regarding genetics and chemistry were determined long before anyone had an understanding of how DNA works or how atoms share electrons.

    • DzyMsLizzy profile image

      Liz Elias 4 years ago from Oakley, CA

      What a great ambition you have! I always enjoyed science, but I suck at math...so a science career wasn't in the cards for me...to this day, I'm confined to childish "experiments." LOL

    • leahlefler profile image
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      Leah Lefler 4 years ago from Western New York

      The dish soap makes the foam "flow" a little better, DzyMsLizzy - it makes the foam a little more resilient and it cascades down the sides of the volcano for a slightly longer period of time. It works just fine without the liquid detergent, though - the second or third takes I did with just baking soda and vinegar.

      Lemon juice definitely works. You just need an acid to donate the H+ ion for the reaction. Once you make carbonic acid, the reaction will continue.

      I actually want to start a science club for kids in our area - I have a ton of ideas and really want to spark a love for science, math, and engineering.

    • leahlefler profile image
      Author

      Leah Lefler 4 years ago from Western New York

      The Mentos in Diet Coke are extremely impressive - you get jets of foam instead of a quieter baking soda and vinegar reaction. It is 28 degrees (F) outside at the moment, so we are sticking to the great indoors for our current experiments!

      This is definitely a recipe, bankscottage - just not one you can eat! My poor husband was disappointed when he found a volcano in the oven instead of cookies.

    • DzyMsLizzy profile image

      Liz Elias 4 years ago from Oakley, CA

      Golly--this brings me back to childhood, although, I never had anything so fancy as a dough volcano. We just put the baking soda into the glass of vinegar....and promptly got in trouble for not doing it within the confines of the kitchen sink! Hee hee hee... I was an only child, often the "victim" of pranks by slightly older playmates..I wonder, in retrospect, if my girlfriend already knew what would happen..... ... ...

      We never used dish soap, either, and it worked just fine...I wonder what that adds?

      As a person who always liked to experiment, I found that lemon juice will also work...just not quite as dramatically...

      LOL--I remember the mentos candy experiment as done by the Mythbusters...They got a fountain almost 15 feet high up the side of their building! Impressive, indeed.

      Fun hub--voted up across and shared.

    • bankscottage profile image

      bankscottage 4 years ago from Pennsylvania

      I loved making "volcanoes" as a kid. I'm sure I did it at least once as a science project. I don't think I got as sophisticated as baking it or using acrylic paint. Kids today just use the Mentos in Diet Coke. No sense of tradition. Nice video, very professional looking.

      I'm not much of a cook. Does this count as a recipe Hub? ;-)

      Voted up, interesting, useful, and shared.