Phosphoric acid, H3PO4, crystalline

Phosphate adhesives are made by reacting zinc oxide (ZnO) with phosphoric acid (H3PO4), forming ZnHP043H20 which sets to a crystalline material and is used as a dental cement More elaborate dental materials are constantly being introduced and tested as we all verily on our trips to the dentist s office. However, progress is slow because the demands and requirements are high. 

Scammel proposed its separation by means of a definite crystalline compound with phosphoric acid. This body has the composition CioHjgO. H3PO4. The use of phosphoric acid is the basis of the British Pharmacopoeial test for cineol in essential oils. 

One hundred percent H3PO4 is a colorless solid, mp 42°C. The usual laboratory concentration is 85% HjP04, since a crystalline hydrate separates at 88% concentration. Table 2.4 shows the percentages for phosphoric acid use, almost all of which goes to the fertilizer industry. 

Phosphoric acids, strong, 3 85, 89 H3PO4, crystalline, 1 101 H4P2O7, crystalline, by concentration of H3PO4, 3 96 by dilution of H6P40i , 3 97 by solution of PjOs in H3PO4, 3 97... 

Poorly crystalline or amorphous Phosphorite sediments made from the hard remains of marine organisms are the principal commercial source of phosphates, although Apatites are also mined. Treatment of phosphate minerals with sulfuric acid yields superphosphate fertilizer, a mixture of Ca(H2P04)2, H3PO4 and CaS04. Phosphoric acid treatment gives triple superphosphate , rich in Ca(H2P04)2. Other soluble fertilizers such as ammonium phosphates are obtained from these products. 

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