Iron nails are dipped in copper sulphate solution. After some time, the blue colour of the solution fades. (i) Name the type of chemical reaction taking place. (ii) What substance is deposited on the iron nails, and why?
Generated by claude-sonnet-4-6 · 2026-06-26 00:53 · grounding rag
Model Answer
(i) This is a displacement reaction. Iron, being more reactive than copper, displaces copper from copper sulphate solution.
(ii) Copper is deposited on the iron nails (they turn brownish). Iron displaces copper from CuSO₄ solution because iron is more reactive than copper. The reaction is:
$$\text{Fe}(s) + \text{CuSO}_4(aq) \rightarrow \text{FeSO}_4(aq) + \text{Cu}(s)$$
As Cu²⁺ ions are used up, the blue colour of the solution fades.
Source: Chapter 1, Section 1.2.3 — Displacement Reaction
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Explanation
- (i) must name the reaction type clearly — "displacement reaction" is the exact term used in the textbook.
- (ii) Two points are needed for full marks: what is deposited (copper/brownish layer) and why (iron is more reactive, so it displaces copper). Writing the balanced equation strengthens the answer and is expected in board exams.
- The fading of blue colour is due to conversion of CuSO₄ → FeSO₄ (which is pale green/colourless) — mention this to show complete understanding.