How to Make a Model Ammonium Dichromate Volcano

Written by Harry Gilliam

Topics: Science

A while back I received an email from Harry:

“Have you ever made an ammonium dichromate volcano? They are really popular with parents and teachers and look great daytime or night.”

I responded: “Never learned how to make a volcano. Led a deprived childhood. No way they’re doin’ anything like that in science classes nowadays.”

Making a volcano would, of course, be exactly the sort of school project which would capture the imagination of so many young students.

Harry shot back: “Neat little effect. The ammonium dichromate burns by itself, but you can add other fuels to make more lifelike ‘lava.’ For instance, charcoal 10 or 20-mesh. I imagine there’s some flake titanium, ferro-titanium, etc. that would work as well. You could provide volcano formulas for high school projects.”

Well, I was intrigued. I’ve made 16-inch ball shells and 36-inch girandolas, but never an ammonium-dichromate volcano. I couldn’t let that stand for long. So I asked Harry to send me a few tubs of the ammonium dichromate, and I put it on my to-do list.

In the meantime, I did a little research on the Internet, and also found a couple of paragraphs about the volcano in the Skylighter Project Plans pages.

Warning: So, first off, a bit of a warning: Ammonium dichromate is rated as a hazardous toxic chemical on its MSDS. One should not inhale its dust, but that’s not too tough to avoid since it comes as relatively large orange crystals, not a dust that gets easily airborne.

One should not ingest it. Well, Duh!

One should avoid skin contact. Wear rubber gloves if you’re gonna touch the stuff (which is not necessary to create one of these volcanoes). Avoid eye contact. The stuff can cause cancer.

So, exercise appropriate caution with this chemical. If you’re going to be making a volcano like this for a science fair, perform all actions and experiments with it outdoors, and when the volcano is “erupting” don’t allow anyone to breathe the small amount of smoke and ash, which rises off of it.

Use common sense. I know, I know. Common sense is not in common use nowadays to protect folks from harm. Since everything even remotely dangerous is becoming illegal, folks are increasingly being born with no common sense chip. But, use common sense anyway. There, you see? You got me started.

I’m not much of a chemist, but I did find this information interesting, and some other folks might as well.

Ammonium dichromate is sometimes referred to as Vesuvian Fire due to its use in the creation of these small volcano replicas.

Ammonium dichromate’s formula is (NH4)2Cr2O7.

Ammonium Dichromate, Skylighter #CH5500

Ammonium Dichromate, Skylighter #CH5500

When it burns, it decomposes according to the following equation:

(NH4)2Cr2O7 (solid) -> Cr2O3
(solid) + N2 (gas) + 4H2O (gas)

The gaseous byproducts are simple nitrogen gas and steam, so they are innocuous.

Chromium Oxide Ash Left After Ammonium Dichromate Volcano Burns

Chromium Oxide Ash Left After Ammonium Dichromate Volcano Burns

The solid product is chromium (III) oxide. What remains after the volcano burns is this solid, grayish-green ash. The chromium in it is toxic and possibly carcinogenic, so care should be exercised when handling it and disposing of it. Some of this ash flies up into the air when the volcano is burning, so you don’t want anyone close enough to it to breathe the stuff.

The chromium oxide can reportedly be used in a thermite reaction to produce elemental chromium metal, so I’m going to save the chromium oxide ash to try to use it in such a reaction, since I am planning an article on thermite reactions.

Click here to learn how to make a Vesuvian volcano with Ammonium Dichromate.

2 Comments For This Post I'd Love to Hear Yours!

  1. Michael says:

    I learned about this in the 4th grade living in hawaii our teacher did this experiment it was so cool . She gave me a piece of paper withe the chemical name and stil have it to this day!! Now i will show my grandkids what a hoot!!

  2. Michael says:

    This was an absolutly excellent article. I have seen this experiment done in the classroom before but I havn’t seen it at night it looks amazing. I might have to try it for myself.

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