Colorless, transparent tetragonal crystals. Easily soluble in water, slightly soluble in alcohol, insoluble in acetone. Melting point 190℃; fairly stable in air, with a small part decomposing when heated to 100℃. Above the melting point it loses ammonia and water, forming a mixture of ammonium metaphosphate and phosphoric acid.
Mainly used as a fire-proofing agent for wood, paper and fabrics, and also as an additive for fireproof coatings, dry powder extinguishing agents, etc. In the food industry it serves as a leavening agent and nutrient. In agriculture it is used as a chlorine-free N-P compound fertilizer, an excellent base material for formulating N-P-K compound fertilizers, and a high-quality water-soluble fertilizer raw material.
