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2017 O Level Chem P1 Q26 — Qualitative Analysis / Identifying Ions Solution

Qualitative Analysis / Identifying Ions 2017 O Level Pure Chemistry · Paper 1 · Q26

Question

A salt, G, dissolved in water to give a green solution. On adding chlorine, the green solution turned yellow. On addition of aqueous ammonia, the green solution gave a green precipitate and the yellow solution gave a red-brown precipitate. On addition of dilute nitric acid followed by aqueous barium nitrate, the green solution gave a white precipitate. What is the formula of G?

ACuCl₂
BCuSO₄
CFeCl₂
DFeSO₄

Correct answer: D

Video Solution

Explanation

Answer: D. The green solution is iron(II); chlorine oxidises it to yellow iron(III). With aqueous ammonia, iron(II) gives a green precipitate and iron(III) gives a red-brown precipitate, matching the observations.

The white precipitate with nitric acid and barium nitrate shows a sulfate. So G is iron(II) sulfate, \(\text{FeSO}_4\).

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