Ammonium dihydrogen phosphate

Chemical properties

Ammonium dihydrogen 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.

Physical properties

White crystalline powder; odorless; density 1.80 g/cm³; readily dissolves in water (40 g/ 100 g); pH of 0.2 molar solution 4.2; slightly soluble in alcohol; insoluble in acetone.

Physical properties

Electrooptic coefficient (cm/stat-volt): γ₆₃=-2.54×10^-7, γ₄₁₌62×10^-7
Dielectric constants: ε₀=56.4–55.9 (10² –10⁸ Hz, E⊥C), 16.4–13.7 (10² –10 Hz, E//C).

The Uses of Ammonium dihydrogen phosphate

Ammonium dihydrogen phosphate is a general purpose food additive which is readily soluble in water. A 1% solution has a ph of 4.3–5.0. It is used as a dough strengthener and leavening agent in baked goods and as a firming agent and ph control agent in condiments and puddings. It is also used in baking powder with sodium bicarbonate and as a yeast food.

Definition

ChEBI: The ammonium salt of phosphoric acid (molar ratio 1:1).

Preparation

Ammonium dihydrogen phosphate is obtained by reaction of equimolar amounts of ammonia and phosphoric acid:
NH₃ + H₃PO₄ → (NH₄)H₂PO₄.

General Description

Ammonium dihydrogen phosphate (APM) is an inorganic salt widely used in fertilizer, baking powder and yeast production. It is also employed as an agent to control pH of a solution and in corrosion inhibition. APM can be prepared by reacting phosphoric acid with anhydrous ammonia maintaining the pH below 5.8. The change in some of the physical characteristics on its addition to a high carbonate containing unfired and fired illitic shale has been studied.

Flammability and Explosibility

Not classified

Agricultural Uses

Ammonium phosphate fertilizers are highly soluble in water and fast acting in soil to give nitrogen and phosphorus in a chemical combination. They form an important base for many compound fertilizers. Ammonium phosphates, particularly Ammonium dihydrogen phosphate(DAP), are the most popular phosphate fertilizers worldwide because of their high utility and good physical properties. The standard commodity grade of diammonium phosphate is 18-46-0. Pure and completely soluble ammonium phosphates are used mainly as liquid fertilizers.

Biochem/physiol Actions

Ammonium dihydrogen phosphate exhibits non-linear optical (NLO) and electro-optic (EO) properties.

Potential Exposure

Used in fireproofing of textiles; wood and paper; in soldering flux; as a fertilizer; a buffer; in baking powder and food additives.

Shipping

There are no DOT/UN listed requirements.

Purification Methods

Crystallise it from water (0.7mL/g) between 100o and 0o.

Incompatibilities

Ammonium dihydrogen phosphate is incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Contact with air causes this chemical to produce anhydrous ammonia fumes.

Waste Disposal

May be flushed to sewer with huge volumes of water.