B02 Ammonium Dichromate Volcano

Description
Ammonium dichromate is set off by igniting a paper towel which has been soaked in ethanol. A voluminous green chromium(III) oxide ash is thrown out of the pile of dichromate with bright sparks. This experiment is shown twice--once in the dark and once in normal light. The ash is very toxic because some carcinogenic chromium(VI) is not reduced to chromium(III) before it is expelled from the hot center of the reaction.

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

Reference
B. Z. Shakhashiri, "Chemical Demonstrations", Vol. 1, The University of Wisconsin Press, Madison ,Wisconsin, (1983) p.81.