Chemistry 5070 · O Level · Identification of ions and gases

Identification of ions and gases — practice question

The solution contains two different cations plus one anion.
(a)[6]

Fill in the table. Identify any gases produced and explain the tests used to recognise these gases.

(b)[6]

Ammonium sulfite, $(\text{NH}_4)_2\text{SO}_3$, is soluble in water. Aqueous ammonium sulfite is slowly oxidised by oxygen in the air. Therefore, aqueous ammonium sulfite will also include some sulfate ions, $\text{SO}_4^{2-}$. Describe a sequence of tests, together with the observations, to show the presence of ammonium ions, sulfite ions and sulfate ions in this solution. Your answer must make it clear which ion is identified by each test.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: chromium(III) ion ($\text{Cr}^{3+}$)

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