Erupting Volcanoes: Science Saturday - Eva Varga

February 14, 20099
We did a few mini-experiments this afternoon to learn more about volcanoes. Unfortunately, I don’t yet have safety goggles for each of the kiddos so I improvised. We may look silly in our snow goggles, but we are safe! 🙂


When you add baking soda to vinegar, a reaction occurs which makes lots of fizz and foam! What actually happens is this: the acetic acid (CH3COOH, and the thing that makes vinegar sour) reacts with sodium bicarbonate (NaHCO3, or baking soda) to form carbonic acid (H2CO3).

It’s a double replacement reaction, and is also a neutralization reaction. Carbonic acid is unstable, and it immediately falls apart into carbon dioxide (CO2) and water (H2O). The bubbles you see from the reaction come from the carbon dioxide escaping the solution that is left. Carbon dioxide is heavier than air, so, it flows almost like water when it overflows the container. The overall balanced reaction is this:

NaHCO3 + CH3COOH —> CH3COONa + H2O + CO2


To do this experiment, you’ll need ammonium dichromate, (NH4)2Cr2O7, an orange crystalline solid at room temperature, which resembles slightly, table sugar. It can be ignited with high heat, such as that from a bunsen burner or a match. As it burns, the dark green solid “fluff” that forms is Cr2O3. The orange, ammonium dichromate, (NH4)2Cr2O7,is decomposed according to the balanced equation below:

(NH4)2Cr2O7(s) —-> Cr2O3(s) + N2(g) + 4H2O(g)


  • School for Us

    February 12, 2009 at 3:00 am

    I think the goggles are cute! 🙂 Also, I’ve never seen a volcano demo where you lit it on fire. Is this a kit? Did you make the volcanos yourself? And, how did you do it differently so you could light it on fire? thanks!

  • Makita

    February 12, 2009 at 3:07 am

    I saved a small ziploc baggie of Ammonium dichromate from when I was teaching. You might be able to get a little from a local jr high or high school. Explain what you plan to do with it… you’ll only need about a teaspoon (depending on the size of your volcano).

  • Makita

    February 12, 2009 at 3:08 am

    I simply put a teaspoon of it in the crater of the volcano (it was shallow) and lit it. It will ignite on its own after a bit.

  • Eluciq

    February 12, 2009 at 3:23 am

    the goggles are way to funny as your safety glasses…BIG GRINS!

    What a fun project to do with your kiddo’s!

  • Cellista

    February 13, 2009 at 4:52 am

    What great videos! I still have “make a volcano” on my to-do list sometime this year. My boys would really love that second one.

  • School for Us

    February 15, 2009 at 2:47 am

    Hi again. 🙂 Can you just email me? I have more questions. Thanks!
    drleeds at sbcglobal dot net

  • Pebblekeeper

    February 15, 2009 at 4:29 pm

    Is there someplace besides the school to get the volcano supplies? The boys would real like the second one! I LOVE the expectation in your son’s face and movements!!!

  • Mom2Amara

    February 16, 2009 at 6:26 pm

    I love how the kids look in awe as they wait for the volcanoes to erupt!

  • 6atkins

    February 20, 2009 at 1:30 am

    Those were so neat! Thanks for sharing the technical info too! I think snow goggles make great safety glasses! The closest things I could probably come up with are swimming goggles! 🙂

    I also enjoyed your comparison of Classical and Charlotte Mason. I tend to be somewhere between the two myself, though recently I fall more to the CM side.

    Blessings, Eva

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