Ammonium perchlorate

Ammonium perchlorate ("AP") is an inorganic compound with the formula NH₄ClO₄. 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.

Ammonium perchlorate

Ammonium perchlorate
Unit cell of the crystal structure
Names
IUPAC name Ammonium perchlorate
Other names AP
Identifiers
CAS Number	7790-98-9 Y
3D model (JSmol)	Interactive image
ChemSpider	23041 Y
ECHA InfoCard	100.029.305
EC Number	232-235-1
PubChem CID	24639
RTECS number	SC7520000
UNII	Z3DQ8VD57X
UN number	1442
CompTox Dashboard (EPA)	DTXSID4024515
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
SMILES [O-]Cl(=O)(=O)=O.[NH4+]
Properties
Chemical formula	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]
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, ethanol Insoluble in diethyl ether[3]
Structure
Crystal structure	Orthorhombic (<240 °C) Cubic (>240 °C)
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	−295.77 kJ/mol[4]
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H201, H271, H319, H373
Precautionary statements	P210, P220, P221, P230, P240, P250, P260, P264, P280, P283, P305+P351+P338, P306+P360, P314, P337+P313, P370+P378, P370+P380, P371+P380+P375, P372, P373, P401, P501
NFPA 704 (fire diamond)	1 0 2 OX
Safety data sheet (SDS)	External MSDS[5]
Related compounds
Other anions	Ammonium chlorate Ammonium chloride
Other cations	Potassium perchlorate Sodium perchlorate Lithium perchlorate
Related compounds	Perchloric acid Ammonium perbromate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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.^[6]

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.^[7] 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^[8] and is classified as an explosive for particle sizes less than 15 micrometres.^[9][10]

Applications

During World War I England and France used mixtures featuring ammonium perchlorate (such as "balstine") as a substitute high explosive.^{[citation needed]}

The primary use of ammonium perchlorate is in making solid rocket propellants.^[11] 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.^{[citation needed]}

Some "breakable" epoxy adhesives contain suspensions of AP. Upon heating to 300°C, the AP degrades the organic adhesive, breaking the cemented joint.^{[citation needed]}

Toxicity

Perchlorate itself confers little acute toxicity. For example, sodium perchlorate has an LD₅₀ of 2–4g/kg and is eliminated rapidly after ingestion.^[6] 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.^{[citation needed]}