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Ammonium perchlorate ("AP") is an inorganic compound with the formula Template:Nowrap. It is a colorless or white solid that is soluble in water. It is a powerful oxidizer. Combined with a fuel, it can be used as a rocket propellant called ammonium perchlorate composite propellant. Its instability has involved it in accidents such as the PEPCON disaster.
ProductionEdit
Ammonium perchlorate (AP) is produced by reaction between ammonia and perchloric acid. This process is the main outlet for the industrial production of perchloric acid. The salt also can be produced by salt metathesis reaction of ammonium salts with sodium perchlorate. This process exploits the relatively low solubility of NH4ClO4, which is about 10% of that for sodium perchlorate.<ref name=Ullmann>Helmut Vogt, Jan Balej, John E. Bennett, Peter Wintzer, Saeed Akbar Sheikh, Patrizio Gallone "Chlorine Oxides and Chlorine Oxygen Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH. {{#invoke:doi|main}}</ref>
AP crystallises as colorless rhombohedra.
DecompositionEdit
Like most ammonium salts, ammonium perchlorate decomposes before melting. Mild heating results in production of hydrogen chloride, nitrogen, oxygen, and water.
- 4 NH4ClO4 → 4 HCl + 2 N2 + 5 O2 + 6 H2O
The combustion of AP is quite complex and is widely studied. AP crystals decompose before melting, even though a thin liquid layer has been observed on crystal surfaces during high-pressure combustion processes.<ref>Template:Cite journal</ref> Strong heating may lead to explosions. Complete reactions leave no residue. Pure crystals cannot sustain a flame below the pressure of 2 MPa.
AP is a Class 4 oxidizer (can undergo an explosive reaction) for particle sizes over 15 micrometres<ref>NFPA 400: Hazardous Materials Code, 2010</ref> and is classified as an explosive for particle sizes less than 15 micrometres.<ref>NFPA 495: Explosive Materials Code, 2010</ref><ref>"Development of an Enhanced Hazard Classification System for Oxidizers Research Project, Technical Report", Safety Engineering Laboratories, Inc., The Fire Protection Research Foundation, 13 April 2006</ref>
ApplicationsEdit
During World War I England and France used mixtures featuring ammonium perchlorate (such as "balstine") as a substitute high explosive.
The primary use of ammonium perchlorate is in making solid rocket propellants.<ref>"Perchlorate: Overview of Issues, Status, and Remedial Actions" Template:Webarchive, ITRC, September 2005</ref> When AP is mixed with a fuel (like a powdered aluminium and/or with an elastomeric binder), it can generate self-sustained combustion at pressures far below atmospheric pressure. It is an important oxidizer with a decades-long history of use in solid rocket propellants – space launch (including the Space Shuttle Solid Rocket Booster), military, amateur, and hobby high-power rockets, as well as in some fireworks.
Some "breakable" epoxy adhesives contain suspensions of AP. Upon heating to 300°C, the AP degrades the organic adhesive, breaking the cemented joint.
ToxicityEdit
Perchlorate itself confers little acute toxicity. For example, sodium perchlorate has an Template:LD50 of 2–4g/kg and is eliminated rapidly after ingestion.<ref name=Ullmann/> However, chronic exposure to perchlorates, even in low concentrations, has been shown to cause various thyroid problems, as it is taken up in place of iodine.