In a previous blog post, we talked about how silver metal can be chemically transformed into silver fulminate, which is such a ridiculously sensitive explosive that it can’t be mass produced (beyond a few milligrams) or transported). To put it lightly, stability is a lot to ask of silver fulminate. But, it does have a niche use as a common children’s toy: the bang-snap.
Surely you’ve seen bang-snaps around New Year’s or Independence Day or played with them as a kid. They’re the tiny teardrop-shaped paper firecrackers that pop like a cap gun when you toss them on the ground. That pop, or detonation, is made possible with silver fulminate.
The main ingredient in a bang-snap is gravel – about 200 milligrams of it. However, this gravel is impregnated with an extremely small amount (about .08 milligrams) of silver fulminate. The reason why bang-snaps don’t damage anything is because of the gravel. One bang-snap contains about 2500% more gravel than silver fulminate. This inert-to-explosive mass ratio buffers the violent detonation of the silver fulminate so much that it doesn’t damage anything.
Bang-snaps are a safe way to see silver fulminate’s sensitivity first-hand. Just rubbing one in-between your fingers is enough to set it off (it sparks a little, but won’t damage the skin). And that’s just .08 milligrams of the stuff. Now you know why chemistry labs keep the silver nitrate and ethanol far away from each other.
