Ammonium dihydrogen phosphate
ammonium dihydrogen phosphate
|3D model (Jmol)||Interactive image|
|Molar mass||115.02 g·mol−1|
|Melting point||190 °C (374 °F; 463 K)|
|40.4 g/100 mL|
|Solubility||soluble in ethanol
insoluble in acetone
Refractive index (nD)
Std enthalpy of
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|5750 mg/kg (rat, oral)|
Potassium dihydrogen phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Ammonium dihydrogen phosphate (ADP), also known as monoammonium phosphate (MAP), NH4H2PO4, is formed when a solution of phosphoric acid is added to ammonia until the solution is distinctly acidic. It crystallizes in tetragonal prisms. Monoammonium phosphate is often used in the blending of dry agricultural fertilizers. It supplies soil with the elements nitrogen and phosphorus in a form usable by plants. The compound is also a component of the ABC powder in some dry chemical fire extinguishers. This substance is also supplied in an emerald green, amethyst, or aquamarine crystal growing box kit for children.
Solid monoammonium phosphate shows a dissociation pressure of ammonia of 0.05 mm Hg at 125 °C based on the decomposition reaction as follows:
- NH4H2PO4(s) ⇌ NH3(g) + H3PO4(l)
ADP is a widely used crystal in the field of optics due to its birefringence properties. As a result of its tetragonal crystal structure, this material has negative uniaxial optical symmetry with typical refractive indices no = 1.522 and ne = 1.478 at optical wavelengths.
ADP crystals are piezoelectric, a property required in some active sonar transducers (the alternative being transducers that use magnetostriction). In the 1950s ADP crystals largely replaced the quartz and Rochelle salt crystals in transducers because they are easier to work than Quartz and, unlike Rochelle Salt, are not deliquescent.
|This article needs additional citations for verification. (July 2009) (Learn how and when to remove this template message)|
- Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–40. ISBN 0-8493-0594-2.
- "Monoammonium Phosphate (MAP)" (PDF). www.mosaicco.com. Retrieved 2015-06-05.
- IPNI. "Monoammonium Phosphate (MAP)" (PDF). www.ipni.net. International Plant Nutrition Institute. Retrieved 21 July 2014.
- John R Van Wazer (1958). Phosphorus And Its Compounds - Volume I: Chemistry. New York: Interscience Publishers, Inc. p. 503.
- Amnon Yariv, Pochi Yeh (1984). Optical Waves in Crystals. Wiley, Inc.
- Willem Hackmann (1984). Seek and Strike: Sonar, Anti-Submarine Warfare and the Royal Navy, 1914–1954. Her Majesty's Stationery Office. ISBN 0-11-290423-8.