NH4NO3

Ammonium nitrate (NH4NO3) is a white, odorless crystalline inorganic compound. It is highly soluble in water and moderately hygroscopic. It melts at 169.6°C and then decomposes, releasing gases; as an oxidizer, it can intensify combustion of fuels.

Commercially it is produced by reacting nitric acid with ammonia and crystallizing the result into prilled or granular solids. The material typically contains about 34-35% nitrogen by weight. It is widely used as a nitrogen fertilizer in agriculture and horticulture.

Ammonium nitrate also serves as an oxidizer in explosives, notably in formulations such as ammonium nitrate fuel oil (ANFO). In some applications it is used in instant cold packs due to the endothermic dissolution of the solid in water.

Safety and regulation: It is a strong oxidizer; confinement, high heat, or contamination with organic materials can lead to explosive outcomes. Because it is water-soluble, spills can contaminate groundwater and contribute to eutrophication. Due to past incidents involving improper handling and storage, many countries regulate production, storage, and transfer, and require appropriate licensing, secure storage, and separation from fuels and incompatible substances. Handling guidelines emphasize keeping it cool, dry, and away from incompatible materials. Production and transport are typically subject to safety and security controls to mitigate the risk of misuse.