'Ammonium phosphate' - Molar Mass = 149.12g/mol. The normal
ammonium phosphate, (NH
4)
3PO
4, is obtained as a crystalline powder, on mixing concentrated solutions of ammonia and
phosphoric acid, or on the addition of excess of
ammonia to the acid phosphate (NH
4)
2HPO
4. It is soluble in water, and the aqueous solution on boiling loses ammonia and the acid phosphate NH
4H
2PO
4 is formed.
Ammonium phosphate is used as an ingredient in some
fertilizers as a high source of elemental
nitrogen.
'Diammonium hydrogen phosphate', or
diammonium phosphate, (NH
4)
2HPO
4, is formed by evaporating a solution of phosphoric acid with excess of ammonia. It crystallizes in large transparent prisms, which melt on heating and decompose, leaving a residue of metaphosphoric acid, (HPO
3).
'Ammonium dihydrogen phosphate', or 'monoammonium phosphate', NH
4•H
2PO
4, is formed when a solution of phosphoric acid is added to ammonia until the solution is distinctly
acid. It crystallizes in quadratic 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 which is usable by plants. The compound is also a component of the ABC powder in some dry powder
fire extinguishers.
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