Silver fulminate
) is an
ionic compound of
silver and the
fulminate anion. It has
CAS number 5610-59-3.
It is a
primary explosive that has very little practical value due to its extreme sensitivity. The impact of a single
water droplet has been known to detonate several
milligrams of silver fulminate. Even small amounts of this explosive can cause extensive
shrapnel damage, and should be treated with extreme caution. Silver fulminate is often confused with fulminating silver, a decomposition product of
Tollen's reagent. Fulminating silver does not contain the fulminate anion, although it is also an explosive compound.
Silver fulminate is used in "trick noise-makers", a popular type of novelty
firework.
Only very tiny amounts of silver fulminate should be prepared at once, the weight of the crystals can cause them to self detonate. Silver fulminate was first prepared in 1800 by Edward Howard in his research project to prepare a large variety of fulminates. For 200 years it has been only useful as a curiosity explosive in toys and tricks.
Heat 8 mL of 70%
nitric acid in a 100-mL beaker to 35-38 °C. Add 1 g of silver metal to the acid. While the silver is dissolving it will produce toxic
nitrogen dioxide fumes, use a fume hood or get to a well ventilated area. Some heating may be required to get all of the silver to dissolve. Put 15 mL of 95% ethyl alcohol in a 500-mL beaker set into a salt-ice bath. After the silver has dissolved, slowly add the solution to the alcohol while keeping the temperature below 18 °C. More toxic nitrogen dioxide will be released. The reaction should require about 25-30 minutes to complete, after which 200 mL of cold water is added to precipitate the silver fulminate. Decant off as much of the liquid as possible then drown the crystals with water. Filter to collect the crystals and wash them with 30 mL of ethyl alcohol. Flour or starch can be added to the crystals before filtering to add some degree of stability. Store the silver fulminate away from sunlight as it can decompose. You will need a graduated cylinder for measuring liquids, and a thermometer to monitor the temperature.
