Sodium ammonium orthophosphates preparation

Orthophosphate salts are generally prepared by the partial or total neutralization of orthophosphoric acid. Phase equiUbrium diagrams are particularly usehil in identifying conditions for the preparation of particular phosphate salts. The solution properties of orthophosphate salts of monovalent cations are distincdy different from those of the polyvalent cations, the latter exhibiting incongment solubiUty in most cases. The commercial phosphates include alkah metal, alkaline-earth, heavy metal, mixed metal, and ammonium salts of phosphoric acid. Sodium phosphates are the most important, followed by calcium, ammonium, and potassium salts. 

Pyro- and metaphosphates give the ammonium molybdate test on warming for some time this is doubtless due to their initial conversion in solution into orthophosphates. The chief differences between ortho-, pyro- and metaphosphates are incorporated in the following table. The student should carry out all the tests. To study these reactions use freshly prepared solutions of sodium pyrophosphate and sodium metaphosphate. 

Suggested ammonium phosphate to fireproof theatre curtains Heteropolyacids discovered Sodium pyrophosphate Na4P207 first characterised First P-containing striking matches Preparation of first metal-phosphine complex Historical classification of orthophosphates, pyrophosphates and metaphosphates. Glassy metaphosphates reported Observed enzyme activity in test tubes and first enzyme diastase discovered... 

Example 2 Another example is provided by the pH calculation of an ammonium phosphate solution of analytical concentration 10 mol/L. (This solution would have been prepared by dissolution of 10 mol/L of sodium orthophosphate P04Na3 and 3 x 10 mol/L of ammonium chloride to obtain finally one liter of solution.) The preponderance area andpKa values are given in Fig. 5.8. 

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