Silver nitride is an explosive chemical compound with symbol Ag₃N. It is a black, metallic-looking solid which is formed when silver oxide or silver nitrate

Silver nitrate

Silver nitrate is an inorganic compound with chemical formula . This compound is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides...

  is dissolved in concentrated solutions of ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

, causing formation of a silver-amide

Amide

In chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...

 or imide

Imide

In organic chemistry, an imide is a functional group consisting of two carbonyl groups bound to nitrogen. These compounds are structurally related to acid anhydrides. The relationship between esters and amides and between imides and anhydrides is analogous, the amine-derived groups are less reactive...

 complex which subsequently breaks down to Ag₃N. The standard free energy of the compound is about +315 kJ/mol, making it an endothermic

Endothermic

In thermodynamics, the word endothermic describes a process or reaction in which the system absorbs energy from the surroundings in the form of heat. Its etymology stems from the prefix endo- and the Greek word thermasi,...

 compound which decomposes explosively to metallic silver and nitrogen gas.

History

Silver nitride was formerly referred to as fulminating silver

Fulminating silver

Fulminating silver is the name given to a number of explosive silver-containing substances that "fulminate" or detonate easily and violently."Fulminating silver" has no exact chemical or dictionary definition.It may refer to:...

, but this can cause confusion with silver fulminate

Silver fulminate

Silver fulminate is an explosive, ionic, fulminic acid salt of silver.Silver fulminate is a primary explosive that has very little practical value due to its extreme sensitivity to impact, heat, pressure and electricity...

, or silver azide

Silver azide

Silver azide is the chemical compound with the formula AgN3. This colorless solid is a well-known explosive.-Structure and chemistry:Silver azide can be prepared by treating an aqueous solution of silver nitrate with sodium azide...

, other compounds which have also been referred to by this name. The fulminate and azide compounds do not form from ammoniacal solutions of Ag₂O.

Properties

Silver nitride is poorly soluble in water, but decomposes in mineral acids; decomposition is explosive in concentrated acids. It also slowly decomposes in air at room temperature and explodes upon heating to 165 °C.

Hazards

Silver nitride is often produced inadvertently during laboratory experiments involving silver compounds and ammonia, leading to surprise detonations. Whether silver nitride is formed depends on the concentration of ammonia in the solution. Silver oxide in 1.52 M ammonia solution readily converts to the nitride, while silver oxide in 0.76 M solution does not form nitride. Silver oxide can also react with dry ammonia to form Ag₃N. Silver nitride is more dangerous when dry; dry silver nitride is a contact explosive

Contact explosive

Contact explosive generally refers to any substance that will explode when relatively small quantities of energy are applied to the substance, whether that be heat, light, sound, or physical pressure and even Alpha radiation.Examples include:...

 which may detonate from the slightest touch, even a falling water droplet. It is also explosive when wet, although less so, and explosions do not propagate well in wet deposits of the compound. Because of its long-term instability, undetonated deposits of Ag₃N will lose their sensitivity over time.

Silver nitride may appear as black crystals, grains, crusts, or mirrorlike deposits on container walls. Suspected deposits may be dissolved by adding dilute ammonia or concentrated ammonium carbonate

Ammonium carbonate

Ammonium carbonate is a commercial salt with the chemical formula 2CO3. It is used when crushed as a smelling salt. It can be crushed when needed in order to revive someone who has fainted...

 solution, removing the explosion hazard.

Other uses of the term

The name "silver nitride" is sometimes also used to describe a reflective coating consisting of alternating thin layers of silver metal and silicon nitride

Silicon nitride

Silicon nitride is a chemical compound of silicon and nitrogen. If powdered silicon is heated between 1300° and 1400°C in an atmosphere of nitrogen, trisilicon tetranitride, Si3N4, is formed. The silicon sample weight increases progressively due to the chemical combination of silicon and nitrogen...

. This material is not explosive, and is not a true silver nitride. It is used to coat mirrors and shotgun

Shotgun

A shotgun is a firearm that is usually designed to be fired from the shoulder, which uses the energy of a fixed shell to fire a number of small spherical pellets called shot, or a solid projectile called a slug...

s.