Ammonium perchlorate

Ammonium perchlorate
IUPAC name Ammonium perchlorate
Other names AP
Identifiers
CAS number	7790-98-9 Y
ChemSpider	23041 Y
EC number	232-235-1
UN number	1442
RTECS number	SC7520000
Jmol-3D images	Image 1
SMILES [O-]Cl(=O)(=O)=O.[NH4+]
InChI InChI=1S/ClHO4.H3N/c2-1(3,4)5;/h(H,2,3,4,5);1H3 Y Key: HHEFNVCDPLQQTP-UHFFFAOYSA-N Y InChI=1/ClHO4.H3N/c2-1(3,4)5;/h(H,2,3,4,5);1H3 Key: HHEFNVCDPLQQTP-UHFFFAOYAD
Properties
Molecular formula	NH4ClO4
Molar mass	117.49 g/mol
Appearance	white granular
Density	1.95 g/cm3
Melting point	Exothermic decomposition before melting at >200 °C[1]
Solubility in water	11.56 g/100 mL (0 °C) 20.85 g/100 mL (20 °C) 57.01 g/100 mL (100 °C)
Solubility	soluble in methanol partially soluble in acetone insoluble in ether
Structure
Crystal structure	Orthorhombic (< 513 K) Cubic (> 513 K)
Hazards
MSDS	External MSDS
EU Index	017-009-00-0
EU classification	Oxidant (O)
R-phrases	R9, R44
S-phrases	(S2), S14, S16, S27, S36/37
NFPA 704	0 1 4 OX
Related compounds
Other anions	Ammonium chlorate Ammonium chloride
Other cations	Potassium perchlorate Sodium perchlorate Lithium perchlorate
Related compounds	Perchloric acid
Y perchlorate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Ammonium perchlorate is an inorganic compound with the formula NH₄ClO₄. It is the salt of perchloric acid and ammonia. It is a powerful oxidizer, which is why its main use is in solid propellants. It has been implicated in a number of industrial accidents.

Production

Ammonium perchlorate (AP) is produced by reaction between ammonia and perchloric acid, and is the driver behind the industrial production of perchloric acid. It also can be prepared by treatment of ammonium salts with sodium perchlorate. This process exploits the fact that the solubility of NH₄ClO₄ is about 10% of that for sodium perchlorate.^[2]

AP crystallises into colorless rhombohedra.

Decomposition

Like most ammonium salts, ammonium perchlorate decomposes before melting. Mild heating results in the evolution of chlorine, nitrogen, oxygen, and water.

2 NH₄ClO₄ → Cl₂ + N₂ + 2 O₂ + 4 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.^[3] Strong heating may lead to explosions. Complete reactions leave no residue. Pure crystals cannot sustain a flame below the pressure of 20 bar (2 MPa).

AP is a Class 4 oxidizer (can undergo an explosive reaction) for particle sizes over 15 micrometres^[4] and is classified as an explosive for particle sizes less than 15 micrometres.^[5][6]

Applications

The vast majority of ammonium perchlorate is used to make solid propellants.^[7] When AP is mixed with a fuel (like a powdered aluminum and/or with an elastomeric binder), it can generate self-sustained combustion at far under 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.

Toxicity

Perchlorate itself confers little acute toxicity. For example, sodium perchlorate has an LD₅₀ of 2-4 g/kg and is eliminated rapidly after ingestion.^[2] 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.

See also

• PEPCON disaster

References

1. ^ Liu, L.; Li, F.; Tan, L.; Ming, L.; Yi, Y. (2004), "Effects of Nanometer Ni, Cu, Al and NiCu Powders on the Thermal Decomposition of Ammonium Perchlorate", Propellant, Explosives, Pyrotechnics 29: 34–38, doi:10.1002/prep.200400026 
2. ^ ^{a b} 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. doi:10.1002/14356007.a06_483
3. ^ T. L. Boggs, Deflagration Rate, Surface Structure and Subsurface Profile of Self-Deflagrating Single Crystals of Ammonium Perchlorate. AIAA Journal, 8(5), 1970, pp. 867--873.
4. ^ NFPA 400: Hazardous Materials Code, 2010
5. ^ NFPA 495: Explosive Materials Code, 2010
6. ^ "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
7. ^ "Perchlorate: Overview of Issues, Status, and Remedial Actions", ITRC, September 2005 accessed 4 July 2011