Ammonium dihydrophosphate

Ammonium dihydrophosphate ;
Names:	ammonium dihydrogen phosphate; monoammonium phosphate; ADP; MAP;
Formula:	NH4H2PO4;
Molar mass:	115.025 g/mol;
Density:	1.8 g/cm3;
Crystal system:	tetragonal; a=7.4997 Å, b=7.4997 Å, c=7.5493 Åα=90°, β=90°, γ=90°;
Shapes:	https://en.crystalls.info/w/uploads/media/2/28/Prolongated_tetragonal_pyramidal_prism.json Prolongated tetragonal pyramidal prism https://en.crystalls.info/w/uploads/media/5/50/Beveled_tetragonal_prism.json Beveled tetragonal prism https://en.crystalls.info/w/uploads/media/5/52/Needle.json Needle ;
Color:	colorless;
Melting point:	190 °C463.15 K <br />374 °F <br />833.67 °R <br />;
Decomposition point:	250 °C523.15 K <br />482 °F <br />941.67 °R <br />;
Refractive index:	1.525 ;
Optical properties:	birefringence;
Electricity properties:	piezoelectric; ferroelectric; dielectric;
Stability:	stable;
Hardness:	relatively strong; (2 on Moh's scale);
Toxicity:	non-toxic; LD50=5750mg/kg

Description

Inorganic compound, acid salt of ammonium ion and inorganic phosphoric acid. Doesn't form water hydrates.

Minerals

Occurs in nature as biphosphammite and archerite minerals.

Where to buy

Can be bought in fertilizers store (as "ammophos").

Precursors

Reaction between ammonia and phosphoric acid

Chemical equation:

NH₄OH + H₃PO₄ = NH₄H₂PO₄ + H₂O

For preparation of 100.00g of ammonium dihydrophosphate а 121.87g of

25%25%
10%

ammonia and 100.23g of 85%85% phosphoric acid is required.

Add hot acid to the flask, then add small parts of ammonium compound with stirring until heating will stop (attention, the solution may boil!) . After reaction will stop, filter the solution and use it for crystal growing.

Influence of impurities

Small addition of baking soda or ammonia improves crystal form and transparency.

Influence of pH level

Sharp or needle crystals are forming at lower pH.

Notes

Crystalverse.com site provides a step-by-step guide about growing crystals of ammonium dihydrophosphate.

Storage conditions

Keep in its original form or under several layers of varnish at average humidity and room temperature. Do not keep crystals near heaters.

Solubility

TableGraph

Temperature	g/`100,00` g water
0°C273.15 K <br />32 °F <br />491.67 °R <br />	`22.6`
10°C283.15 K <br />50 °F <br />509.67 °R <br />	`28`
20°C293.15 K <br />68 °F <br />527.67 °R <br />	`35.3`
25°C298.15 K <br />77 °F <br />536.67 °R <br />	`39.5`
30°C303.15 K <br />86 °F <br />545.67 °R <br />	`43.9`
40°C313.15 K <br />104 °F <br />563.67 °R <br />	`56.7`
60°C333.15 K <br />140 °F <br />599.67 °R <br />	`82.5`
80°C353.15 K <br />176 °F <br />635.67 °R <br />	`118.3`
100°C373.15 K <br />212 °F <br />671.67 °R <br />	`173.2`

Soluble in ethanol. Insoluble in acetone.

Gallery

Video

Sources

Ammonium compounds
Salts	Ammonium citrate ((NH₄)₃C₃H₅O(COO)₃) • Ammonium chloride (NH₄Cl) • Ammonium dichromate ((NH₄)₂Cr₂O₇) • Ammonium dihydrophosphate (NH₄H₂PO₄) • Ammonium nitrate (NH₄NO₃) • Ammonium perrhenate (NH₄ReO₄) • Ammonium sulfate ((NH₄)₂SO₄) • Ammonium succinate ((NH₄)₂C₄H₄O₄) • Ammonium tetraborate ((NH₄)₂B₄O₇) • Ammonium thiocyanate (NH₄NCS)
Double salts	Aluminum-ammonium sulfate (NH₄Al(SO₄)₂) • Calcium-ammonium nitrate (5Ca(NO₃)₂ · NH₄NO₃) • Chromium(II)-ammonium sulfate ((NH₄)₂Cr(SO₄)₂) • Chromium(III)-ammonium sulfate (NH₄Cr(SO₄)₂) • Cobalt(II)-ammonium sulfate ((NH₄)₂Co(SO₄)₂) • Cobalt(III)-ammonium sulfate (NH₄Co(SO₄)₂) • Copper(II)-ammonium sulfate ((NH₄)₂Cu(SO₄)₂) • Iron(II)-ammonium sulfate ((NH₄)₂Fe(SO₄)₂) • Iron(III)-ammonium sulfate (NH₄Fe(SO₄)₂) • Magnesium-ammonium sulfate ((NH₄)₂Mg(SO₄)₂) • Manganese(II)-ammonium sulfate ((NH₄)₂Mn(SO₄)₂) • Manganese(III)-ammonium sulfate (NH₄Mn(SO₄)₂) • Nickel-ammonium sulfate ((NH₄)₂Ni(SO₄)₂) • Sodium-ammonium sulfate (NaNH₄SO₄) • Vanadium(II)-ammonium sulfate ((NH₄)₂V(SO₄)₂) • Vanadium(III)-ammonium sulfate (NH₄V(SO₄)₂) • Zinc-ammonium sulfate ((NH₄)₂Zn(SO₄)₂)
Complexes	Ammines • Ammonium dioxalatocuprate(II) ((NH₄)₂[Cu(C₂O₄)₂]) • Ammonium pentachloroferrate(III) ((NH₄)₂[FeCl₅]) • Ammonium tetrachlorocuprate(II) ((NH₄)₂[CuCl₄]) • Ammonium trioxalatoferrate(III) ((NH₄)₃[Fe(C₂O₄)₃])

Phosphates
Acidic	Ammonium dihydrophosphate (NH₄H₂PO₄) • Copper(II) dihydrophosphate (Cu(H₂PO₄)₂) • Potassium dihydrophosphate (KH₂PO₄) • Potassium hydrophosphate (K₂HPO₄) • Zinc dihydrophosphate (Zn(H₂PO₄)₂)
Neutral	Iron(II) phosphate (Fe₃(PO₄)₂)

Ammonium dihydrophosphate
Names:	ammonium dihydrogen phosphate monoammonium phosphate ADP MAP
Formula:	NH₄H₂PO₄
Molar mass:	115.025 g/mol
Density:	1.8 g/cm³
Crystal system:	tetragonal a=7.4997 Å, b=7.4997 Å, c=7.5493 Åα=90°, β=90°, γ=90°
Shapes:	Prolongated tetragonal pyramidal prism Beveled tetragonal prism Needle
Color:	colorless
Melting point:	190 °C463.15 K <br />374 °F <br />833.67 °R <br />
Decomposition point:	250 °C523.15 K <br />482 °F <br />941.67 °R <br />
Refractive index:	1.525
Optical properties:	birefringence
Electricity properties:	piezoelectric ferroelectric dielectric
Stability:	stable
Hardness:	relatively strong (2 on Moh's scale)
Toxicity:	non-toxic LD₅₀=5750mg/kg