Q1. [2] medium thorough-understanding
Zinc displaces copper from copper sulphate solution, and lead displaces copper from copper chloride solution. However, when a copper strip is placed in zinc sulphate or lead nitrate solution, no reaction is observed. What do these observations tell you about the relative reactivities of zinc, lead, and copper? What broader principle do these observations illustrate?
Generated by claude-sonnet-4-6 · 2026-06-26 00:55 · grounding rag
Model Answer
These observations show that zinc and lead are more reactive than copper. A more reactive metal displaces a less reactive metal from its salt solution. Since copper cannot displace zinc or lead from their salt solutions, copper is less reactive than both zinc and lead.
Broader principle: A more reactive metal displaces a less reactive metal from its salt solution. This is the principle of displacement reactions, based on the activity series.
Source: Chapter 1, Section 1.2.3 Displacement Reaction
Explanation
- The examiner expects you to state the reactivity order (Zn > Cu, Pb > Cu) and explain why no reaction occurs when copper is placed in zinc sulphate or lead nitrate (copper is less reactive, so it cannot displace them).
- Naming the broader principle — "a more reactive metal displaces a less reactive metal from its salt solution" — is essential for full marks.
- Mentioning the activity series by name adds precision and is rewarded.