Ammonium perchlorate

Ammonium perchlorate
Names
IUPAC name
Ammonium perchlorate
Other names
AP
Identifiers
7790-98-9 YesY
3D model (Jmol) Interactive image
ChemSpider 23041 YesY
ECHA InfoCard 100.029.305
EC Number 232-235-1
RTECS number SC7520000
UN number 1442
Properties
NH4ClO4
Molar mass 117.49 g/mol
Appearance White Crystalline [1]
Density 1.95 g/cm3
Melting point Exothermic decomposition before melting at >200 °C[2]
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
Orthorhombic (< 513 K)
Cubic (> 513 K)
Hazards
Safety data sheet External MSDS [3]
Oxidant (O)
R-phrases R9, R44
S-phrases (S2), S14, S16, S27, S36/37
NFPA 704
240 °C (464 °F; 513 K)
Related compounds
Other anions
Ammonium chlorate
Ammonium chloride
Other cations
Potassium perchlorate
Sodium perchlorate
Lithium perchlorate
Related compounds
Perchloric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Ammonium perchlorate ("AP") is an inorganic compound with the formula NH4ClO4. It is colorless or white solid that is soluble in water. Perchlorate is a powerful oxidizer and ammonium is a good fuel. This combination explains the usefulness of this material as a propellant in rockets and missiles. It has been involved in a number of accidents, such as the PEPCON disaster.

Production

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.[4]

AP crystallises as colorless rhombohedra.

Decomposition

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.[5] 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[6] and is classified as an explosive for particle sizes less than 15 micrometres.[7][8]

Applications

The primary use of ammonium perchlorate is in making solid fuel propellants.[9] When AP is mixed with a fuel (like a powdered aluminium 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.[4] 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.

References

  1. MSDS. sigmaaldrich.com. Page 3, 9.1 (a)
  2. 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", Propellants, Explosives, Pyrotechnics, 29: 34–38, doi:10.1002/prep.200400026
  3. Ammonium perchlorate MSDS. Sigma-Aldrich
  4. 1 2 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
  5. Boggs, T. L. (1970). "Deflagration Rate, Surface Structure and Subsurface Profile of Self-Deflagrating Single Crystals of Ammonium Perchlorate". AIAA Journal. 8 (5): 867–873. doi:10.2514/3.5780.
  6. NFPA 400: Hazardous Materials Code, 2010
  7. NFPA 495: Explosive Materials Code, 2010
  8. "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
  9. "Perchlorate: Overview of Issues, Status, and Remedial Actions", ITRC, September 2005
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