Homemade volcanoes are a fun activity for children to learn about chemistry. They do create a mess though, so be careful where you conduct these experiments. Baking soda mixed with vinegar are the classic ingredients for this science fair project favorite activity. Homemade volcano alternatives to baking soda and vinegar are often other ingredients that can be found around the house or at least at a local grocery store. By playing around with the proportions of ingredients in each of the following combinations, you can alternate the powerfulness and length of the volcanic eruption.
Elephant toothpaste is named so because the resulting eruption looks like an elephant's trunk squeezing out toothpaste. To make elephant toothpaste, mix concentrated hydrogen peroxide with any brand of liquid soap. Add red food coloring for a colorful lava illusion. When the hydrogen peroxide breaks down quickly it releases a lot of oxygen. This oxygen mixes with the dish soap, causing a lot of bubbles to form. In order to break down the hydrogen peroxide, a catalyst must be added to the mixture. Catalysts can be potassium iodine, manganese dioxide or potassium sulfate. Each will create a different speed of hydrogen peroxide decomposition, creating either a more subtle stream or a more dramatic explosion.
Mentos candies combined with diet cola will result in a powerful explosion. The soda can spray feet up in the air and will create a sticky mess. If you can find a red, carbonated soda this might work better to mimic the color of lava in a volcano eruption. As soon as the candies are dropped into the 2-liter soda bottle, it will begin to erupt. The eruption is due to the gelatin and gum arabic from the candy dissolving in the soda, causing immediate bubbles due to a release of oxygen from the carbon dioxide of the soda.
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Instead of using vinegar, use ketchup with baking soda. This is perfect for a volcano effect because the ketchup is already the right color. You can also add liquid dish soap to create more bubbles and foam in the eruption. Add water to create the desired thickness for the lava. This will create a long-lasting eruption rather than a powerful jet of an eruption. The creation of carbon dioxide gas, by the mixture of the ketchup and baking soda is what causes the eruption.
Salt and soda works in a similar way to the mentos and diet coke option. The eruption will be much less drastic. Carbon dioxide in sparkling drinks reacts with water and forms carbonic acid which then forms the bubbles. These bubbles form around edges, sometimes seemingly invisible edges in a glass. Salt is formed by small crystals with multiple edges, so that the carbonic acid has many places to react with the water and form more bubbles. In this case, the lava will be fizzy and less dramatic, but equally messy and entertaining.