Verification of phosphate with ammonium molybdate
ammonium molybdate solution
nitric acid 13% C R 34 S (1/2)-23-26-27
burner (preferably alcohol-)
- Safety goggles!
- One adds a spatula-tipful of sodium phosphate and dissolves this with about 1 ml of diluted nitric acid.
- One adds some drops of ammonium molybdate solution and heats the mixture with the burner (caution!) until a yellow coloration occurs, whereby one should take care that the solution does not come to a boil.
- During cooling a yellow ammonium molybdophosphate precipitates. If this should not occur, one adds a little more ammonium molybdate solution and reheats.
- The diluted reactive mixture can be disposed of into the drainage.
Ammonium molybdate forms with phosphate a complex salt which is insoluble and therefore precipitates
(NH4)3[P(Mo3O10)4]-ammonium molybdophosphate (correctly: ammonium dodeka molybdophosphate)
Precipitation of ammonium molybdophosphate
derived from experiment F.13.1, S.66,