Qualitative Analysis – Identifying Anions

In this section, students are required to describe the use of different reagents to identify the following anions: carbonate, chloride, iodide, nitrate and sulfate.

Anion Tests and Observations

QA Anion.jpg

Chemists tap on the idea of salt solubility to identify sulfate, chloride and iodide. Dilute nitric acid is first added to remove any interfering ions. Then, an aqueous solution is added to the test sample. Choose an aqueous solution that will form precipitate with the anion in the test sample. If precipitate is formed, we can confirm the identify of the anion.

Click here to revise on Solubility of Salts

Question

Besides aqueous barium nitrate, what other solution can be added to test for sulfate ions?

Lead(II) nitrate solution. White precipitate of lead(II) sulfate is formed.

Pb(NO3)2 (aq) +  Na2SO4 (aq) → PbSO(s)+ 2 NaNO3 (aq)

Question

Besides aqueous silver nitrate, what other solution can be added to test for chloride ions?

Lead(II) nitrate solution. White precipitate of lead(II) chloride is formed.

Pb(NO3)2 (aq) +  2 NaCl (aq) → PbCl(s)+ 2 NaNO3 (aq)

Learn more about Qualitative Analysis – Identifying Cations

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