Ammonium perchlorate

Ammonium perchlorate
IUPAC name	Ammonium perchlorate
Other names	AP
Identifiers
CAS number	[7790-98-9]
EC number	232-235-1
UN number	1442
RTECS number	SC7520000
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	1 2 4 OX
Related compounds
Other anions	Ammonium chlorate Ammonium chloride
Other cations	Potassium perchlorate Sodium perchlorate Lithium perchlorate
Related compounds	Perchloric acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references

Ammonium perchlorate (AP) is a chemical compound with the formula NH₄ClO₄. It is the salt of ammonia and perchloric acid. Like other perchlorates, it is a powerful oxidizer.

It is produced by reaction between ammonia and perchloric acid, or by double decomposition between an ammonium salt and sodium perchlorate.

It crystallises in colorless rhombohedra with a relative density of 1.95. Like most ammonium salts, it decomposes before melting. Mild heating results in chlorine, nitrogen, oxygen and water, while strong heating may lead to explosions.

The combustion of such compound is quite complex and is widely studied in literature. Ammonium perchlorate crystals decompose before melting, even though a thin liquid layer has been observed on crystal surface during high pressure combustion processes.^[2]

The gaseous decomposition products are in general ammonia- and chlorine-based and can react together generating a thin premixed flame very close to the crystal surface. Pure crystals cannot sustain a flame below the pressure of 20 bar (2 MPa). Nevertheless, the material is considered hazardous if ground under 15 micrometres. When AP is mixed with a fuel (like a metal powder or mixed with a polymeric binder) it can generate self-sustained combustion also far under atmospheric pressure.

It is an important oxidizer used in solid rocket propellants known as Ammonium perchlorate composite propellants (APCP). Uses include the Space Shuttle Solid Rocket Boosters, manufactured by Alliant Techsystems (ATK), as well as many other solid rockets including some fireworks, amateur and hobby high powered rockets, and larger rockets used for space launch and military purposes.

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 
2. ^ 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