Mercury(II) fulminate is prepared by dissolving mercury in nitric acid and adding ethanol to the solution.
Silver fulminate can be prepared in a similar way, but this salt is even more unstable than mercury fulminate; it can even explode under water and is impossible to accumulate in large amounts because it detonates under its own weight.
DecompositionThe thermal decomposition of mercury(II) fulminate can begin at temperatures as low as 100°C, though it proceeds at a much higher rate with increasing temperature.
A possible reaction for the decomposition of mercury(II) fulminate yields carbon dioxide gas, nitrogen gas, and a combination of relatively stable mercury salts:
- Hg(CNO)2 → CO2 + N2 + HgO + Hg(OCN)CN
Whether a piece of fulminated mercury thrown on the floor can generate the explosion shown in "Crazy Handful of Nothin'" is one of the myths tested in MythBusters' Breaking Bad special. When thrown with human force, the 50-gram piece of fulminated mercury they tested failed to explode; though it exploded once fitted with a blasting cap, it did not produce an explosion sufficient to blow out windows as shown on the show.