Two questions: what reaction forms between ammonium nitrate, black iron oxide, and sucrose; and a story related question.
So here's the whole story:
So I was playing around a few months ago and stumbled upon a mixture that generated something similar to Black Snakes (firework). I recently decided to demo this mixture to someone, but I could not find my notes about the experiment, so I decided to try to replicate the mixture from what I remembered.
I am certain that the mixture contained ammonium nitrate, black iron oxide, and some sort of fuel (probably sucrose, impure in the form of powdered sugar). Combining these three ingredients (one part by volume, whatever particle sizes I have), and igniting with a lighter, the mixture does form black snaking ash, and turns red and crumbles as it cools.
Q1: So, what kind of reaction has taken place between the black iron oxide, ammonium nitrate, and sucrose?
If I leave out any one of the ingredients, the ash snake does not form, so all three compounds are definitely involved. If we leave out either the ammonium nitrate or sucrose, little happens with the application of heat.
I haven't had a very good batch since I lost my notes, so maybe I am missing an ingredient, or maybe I just haven't got the right ratios. Q2: Any Suggestions?^
Edit: I have been having more success with this mixture (by volume): 1 part ammonium nitrate 1 part potassium nitrate 2 parts black iron oxide 2 parts sucrose
Mix contents and melt over medium indirect heat (skillet is fine); once it is all melted, immediately remove from heat and form into pellet as it cools. The mixture will reduce in volume by several times. I suggest doing this in small batches since it can self ignite if you are not careful, or do not heat it at the right rate.
If the ammonium nitrate is omitted or substituted by potassium nitrate, the ash does not expand or cohere. So the ammonium nitrate is doing something more than just providing oxygen here. The reduction of iron oxide seems to make the ash less monolithic, and moderate reductions in iron oxide forms snakes that fall apart quickly during production.