Exp 6.1 E - To detect the presence of phosphate ions in aqueous solution

Question 1

Apparatus required (5)

Answer 1

test tube, spatula, wash bottle, hot plate or Bunsen burner

Question 2

Chemicals required (4)

Answer 2

Deionised water, any soluble phosphate salt (e.g. Na2HPO4), ammonium molybdate solution, concentrated nitric acid

Question 3

Explain the 5 steps required for this experiment

Answer 3

1. Fill a test tube to 1/10 full of deionised water.
2. Using a spatula, add a small amount of the phosphate salt to the water. Shake to help dissolve.
3. Pour in ammonium molybdate solution until the test tube is about half full.
4. Using a dropper, add five drops of concentrated nitric acid to the test tube.
5. Place the test tube in warm (about 60 degrees C) water. Observe the yellow precipitate formed.

Question 4

What is the yellow precipitate called?

Answer 4

ammonium phosphomolybdate

Question 5

What is the conclusion of this experiment?

Answer 5

Phosphate ions are present in solution.