Edexcel IGCSEChemistryGeneral Applications10 Marks
A student adds a sample of zinc metal to a solution of copper(II) sulfate. The student observes that the zinc turns black and the solution turns colourless. [Figure 2 shows a reactivity series: K, Na, Ca, Mg, Al, Zn, Fe, Pb, Cu, Ag, Au (decreasing reactivity top to bottom)]
- (a)(i)Explain why the zinc turns black.[1]
- (a)(ii)Explain why the solution turns colourless.[2]
- (b)(i)The equation for the reaction is Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s) State the name of this type of reaction.[1]
- (b)(ii)Deduce which substance is oxidised.[1]
- (b)(iii)Explain, in terms of electrons, what happens to the zinc in this reaction.[2]
- (c)Use Figure 2 to predict what happens when silver metal is added to a solution of copper(II) sulfate. Give a reason for your answer.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- B1 for (a)(i) (black) copper (metal is formed / deposited / coating the zinc)
- M1 for (a)(ii) copper (II) ions / Cu²⁺ (are removed from solution / react / turn into copper atoms / reduced)
- A1 for (a)(ii) (copper(II) ions are) blue
- B1 for (b)(i) displacement / redox
- B1 for (b)(ii) zinc / Zn
- M1 for (b)(iii) zinc (atoms) lose electrons
- A1 for (b)(iii) (become) Zn²⁺ ions
- M1 for (c) no reaction / nothing happens / no change
- A1 for (c) silver is less reactive than copper / silver is below copper (in reactivity series)
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