Be sure to put them in the aqueous waste container, as directed by your instructor. There are two parts to this analysis. Then the resulting solution must be diluted and treated with a reagent, ammonium vanadomolybdate, which forms a yellow compound with phosphate. The intensity of the color depends on the concentration of the phosphate. The solutions are analyzed with a spectrophotometer and the concentration of the phosphate determined using a calibration curve.
More detailed instructions follow.
Put excess H 2 SO 4 in the aqueous waste container. Handle with care. Cover the flask with an inverted 30 ml beaker. Suspend the flask in a larger beaker of water on a hot plate in the hood. Heat the reaction mixture for 30 minutes in boiling water, replenishing evaporated water in the flask as needed.