Mono Ammonium Phosphate
Ammonium dihydrogen phosphate (ADP), also known as monoammonium phosphate (MAP) is a chemical compound with the chemical formula (NH4)(H2PO4). ADP is a major ingredient of agricultural fertilizers and dry chemical fire extinguishers. It also has significant uses in optics and electronics.
Chemical properties
Monoammonium phosphate is soluble in water and crystallizes from it as the anhydrous salt in the tetragonal system, as elongated prisms or needles. It is practically insoluble in ethanol.
Solid monoammonium phosphate can be considered stable in practice for temperatures up to 200 °C, when it decomposes into gaseous ammonia NH
3 and molten phosphoric acid H
3PO
4.At 125 °C the partial pressure of ammonia is 0.05 mm Hg.
A solution of stoichometric monoammonium phosphate is acidic (pH 4.7 at 0.1% concentration, 4.2 at 5%).
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Product Info
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Names | |
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IUPAC name
Ammonium dihydrogen phosphate
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Other names
Monoammonium phosphate
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Identifiers | |
3D model (JSmol)
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ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.028.877 |
EC Number |
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E number | E342(i) (antioxidants, …) |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
H6NO4P | |
Molar mass | 115.025 g·mol−1 |
Appearance | white crystals |
Odor | none |
Density | 1.80 g/cm3 |
Melting point | 190 °C (374 °F; 463 K) |
(g/dL) 28 (10 °C) 36 (20 °C) 44 (30 °C) 56 (40 °C) 66 (50 °C) 81 (60 °C) 99 (70 °C) 118 (80 °C) 173 (100 °C) [2][3] |
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Solubility | insoluble in ethanol[2] insoluble in acetone |
Refractive index (nD)
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1.525 |
Structure | |
tetragonal | |
Thermochemistry | |
Std enthalpy of
formation (ΔfH⦵298) |
−1445.07 kJ/mol[4] |
Hazards | |
GHS labelling: | |
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Warning | |
H319 | |
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |
NFPA 704 (fire diamond) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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5750 mg/kg (rat, oral) |
Related compounds | |
Other anions
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Ammonium phosphate Diammonium phosphate |
Other cations
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Monosodium phosphate Potassium dihydrogen phosphate |
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