Mandatory Experiments

Question 1

How do you test for a Chloride Anion?
Procedure:
Observation:
Conclusion:

Answer 1

1. Add AgNO’³ solution to a solution of the sample. A white precipitate will form
2. Add Ammonia (NH’³) The precipitate will dissolve

Ag+ + Cl- —> AgCL¡

Question 2

How do you test for Sulphate or Sulphite?
Procedure:
Observations:
Conclusion:

Answer 2

Pour 2 test tubes of the solution, one Sulphite, another is Sulphate.

1. Add BaCL’² solution to the solutions of the sample, a white precipitate will form.
2. Add HCl to both. If the precipitate remains its sulphate, otherwise sulfite.

Ba’²+ + SO’⁴ ²- —> BaSO’⁴!
Ba’²+ + SO’³ ²- —> BaSO’³!

Question 3

How to test for a carbonate or hydrocarbonate anion
Procedure:
Observations:
Conclusion:

Answer 3

1. Add dilute HCl to the solid sample, g gas is given off that turns limewater milky.
2. Add MgSO4 to the solutions. If white precipitate forms its carbonate otherwise its hydrocarbonate.

Mg²+ + CO’³ ²- —> MgCO’³¡
Mg²+ + 2HCO’³- —> Mg(HCO’³)’²

Question 4

How to test for a nitrate ion?
Procedure:
Observations:
Conclusion:

Answer 4

Add FeSO4 to a solution of the sample, then add concentrated sulphuric acid.

A brown ring forms at the junction of the 2 liquids.

Brown ring is due to the nitrate anion being present

Question 5

How to test for phosphate anions.
Procedure:
Observations:
Conclusions:

Answer 5

Add ammonium molybdate to a solution of the sample. Then add concentrated nictic acid and warm the solution.

Yellow precipitate is formed

Yellow precipitate is due to the phosphate ion being present