A small mound of ammonium dichromate is ignited so it decomposes with sparks and a dramatic color change from bright orange crystals to dark green chromium(III) oxide, resembling a miniature volcano.

1. Place a heatproof tray or foil-lined ceramic tile inside a working fume hood and set a small, conical mound of ammonium dichromate at the center.
2. Form a shallow crater at the top of the mound and insert a small ignition source such as a few match heads or a preheated metal wire.
3. Ignite remotely using a long lighter or by energizing the hot wire, then step back and observe the sparks, gas release, and the pile expanding into a fluffy green solid.
4. Allow the setup to cool completely before handling any residue.

Volcano Reaction - Ammonium Dichromate Decomposition - MrLundScience:

Volcano of Ammonium Dichromate - Nurd Rage:

📄 The Dichromate Volcano - John Straub: https://people.bu.edu/straub/courses/demomaster/chromates.html

• Use a smaller micro-scale volcano on a watch glass to reduce material and exposure.
• Replace match heads with an electrically heated nichrome wire for controlled, hands-off ignition.

• Conduct all chromium demonstrations in a certified fume hood. Avoid inhalation of dust and vapors.
• Wear splash goggles, lab coat, and appropriate chemical-resistant gloves; tie back hair and remove ignition sources from the area.
• Ammonium dichromate contains hexavalent chromium, which is toxic and a known carcinogen. Minimize quantities and avoid skin contact; do not allow any residue to dry and become airborne.
• Chromium(III) oxide residue and any contaminated foil, paper, or tools must be collected as hazardous waste; do not sweep dry or dispose to drains.
• Keep combustible materials away from the volcano setup; hot solids can ignite nearby items.
• Use remote ignition methods when possible and keep observers at a safe distance behind a shield.
• Decontaminate surfaces with damp disposable wipes that are then placed in hazardous waste; wash hands thoroughly after the activity.

• What are the oxidation states of each element before and after the reaction, and which species are oxidized or reduced?
• What gaseous products drive the “eruption” and fluffiness of the residue in the volcano? (Water vapor and nitrogen gas; the gas flow lofts and disperses the forming chromium(III) oxide.)
• Write the balanced decomposition equation for the volcano and identify the physical states. ((NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + 4 H2O(g); solids form the residue, gases provide the eruptive effect.)