Ammonium sulfide is an inorganic compound commonly encountered as an aqueous solution of (NH4)2S. In practice commercial preparations are liquids that release ammonia and hydrogen sulfide gases when they decompose or are acidified. The mixture has a characteristic rotten–egg odor that can be intense at low concentrations; olfactory detection is unreliable because exposure rapidly causes desensitization. For information about the novelty use that exploits this smell see the stink bomb reference.

Chemical properties and composition

Chemically, ammonium sulfide contains sulfide (S2−) ions paired with ammonium (NH4+) ions. Solutions are often complex: they may contain ammonium hydrosulfide (NH4HS) and free ammonia in equilibrium with dissolved sulfide. On contact with acids or on exposure to air the solution decomposes, releasing ammonia and hydrogen sulfide, both of which are volatile and responsible for most of the compound's hazards. Because of this instability, it is normally stored in sealed containers and handled at low temperatures in well‑ventilated areas; it is also commonly described as an aqueous reagent solution.

Uses and examples

In laboratory chemistry ammonium sulfide is used as a source of sulfide ions to precipitate metal sulfides in qualitative analysis and some syntheses. It can precipitate characteristic colored sulfides of many transition metals and is therefore a useful analytical reagent. Outside the lab it has very limited niche uses; its most visible appearance to the general public is in novelty items that exploit its foul odor. For safety guidance and regulatory details consult authoritative chemical safety resources here.

Hazards, handling and first aid

  • Primary hazards arise from the gases it releases: hydrogen sulfide is highly toxic and can be flammable; ammonia is irritating and corrosive to eyes and respiratory passages.
  • Because people can quickly lose the ability to smell hydrogen sulfide, odor should never be relied on for detecting dangerous concentrations.
  • Work with ammonium sulfide in a fume hood, wear appropriate personal protective equipment, and use gas detection for H2S where relevant.
  • For spills and disposal follow institutional hazardous‑waste procedures; do not neutralize or dilute without consulting safety data sheets and experts.

Distinguishing notes

Commercial "ammonium sulfide" solutions are not pure crystalline salts; they are aqueous mixtures that change composition on standing and exposure to air. Analytical users distinguish between sulfide (S2−) and hydrosulfide (HS−) behavior when predicting precipitates or reactivity. Because of its volatility and toxic decomposition products, ammonium sulfide is treated with caution and is replaced by safer sulfur sources when practical.

For additional technical specifications, handling procedures and legal requirements consult material safety data sheets and local regulations rather than relying on informal descriptions of the compound's odor or novelty uses. See further reading and guidance at odour and detection and other safety pages on hydrogen sulfide.