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Mercury Fulminate

Mercury fulminate is a sensitive primary explosive. In its pure form, it is a white powder. It was a widely used primary a while ago but has now been replaced with less toxic explosives though it is still used at times. The synthesis is rather simple and the reactants needed are fairly common in a standard lab. It is synthesized by the action of excess nitric acid on mercury metal producing Mercury (I) Nitrate. The mercury (I) nitrate and excess nitric acid react with ethanol forming a vast chemical change which ultimately results in fulminic acid.

2HNO3 + Hg ----> HgNO3 + NO2

HNO3 + C2H5OH ----> CH3CHO + HNO2 + H2O

CH3CHO + HNO2 ----> CH2NOCHO + H2O






HNO2 ----> NO + OH- (The nitrogen monoxide will react with the air forming nitrogen dioxide which is why the reaction gives off nitrogen dioxide after a while)

2HONC + OH- + HgNO3 ----> Hg(ONC)2 + HNO3 + H2O

Reaction from COPAE, thank you lacrima for pointing this out to me


Materials Equipment
Mercury Metal 20x150mm test tube
70% Nitric acid 100ml beaker or equivalent
96% Ethanol (I consider absolute ethanol a waste for this) Funnel and filter paper
Ammonia solution (Prep/OTC) litmus paper
Acetic Acid (Prep/OTC)  

Into a 20x150mm testtube (or equivalent), pour 10mls of 70% Nitric acid. Add to this 1 gram of mercury metal. Now, you can leave this and walk away for about 30 minutes or so as the mercury dissolves. Do not try quickening the reaction by heating it up. I have tried this before and managed to get the contents of the testtube on my hands and face (it shot up in the air and rained down on me). Of course, I was using an alcohol burner for this. A water bath might work. Either way, its not neccesary to heat it up, just walk away. The reaction will evolve a bit of nitrogen dioxide gas which is another good reason to go away. After it is done the contents of the testtube will be a greenish-yellow color (it varies). In a 100ml beaker or equivalent device pour 20mls of 96% Ethanol which should be around 25C. If it is not then warm it up, if it is above 25C it will be fine, just use it. Quickly pour the contents of the testube into the beaker container the ethanol and step back. Caution: Never use a testtube for this part of the reaction, it will shoot out and cover your lab table or whatever table you use with small ammounts of the reaction mixture. A lot of a poisonous, flammable gas will be evolved at this time. Also some nitrogen dioxide may be evolved. When the reaction subsides you will see some white crystals in the reaction vessel.

Pour the contents of the reaction vessel through some filter paper to collect the crystals of mercury fulminate. First wash once with some water, and then finally with some ethanol. This is your crude mercury fulminate which can be used as is, or purified. If it is not purified it becomes less storage stable and also less stable all around.

To purify, dissolve your crude mercury fulminate in some concentrated ammonia water. 25mls of 10% should do it. A dark grey solution will form. Run this through a filter to remove any unreacted mercury and other impurities. Add your acetic acid dropwise until the mercury fulminate begins to crystalize. Continue the addition until the solution is neutral (shows no acid nor base on red & blue litmus papers). Add about 50ml of distilled water to this and filter the mercury fulminate out. It should be a white, crystaline powder.

This explosive can also be mixed in a ratio of 9 parts (by weight) mercury fulminate with 1 part (by weight) potassium chlorate (Thank you powerlabs for this information). Load moist into detonators and always ground yourself whenever you're about to handle mercury fulminate.