1. 1
   A jewellery manufacturer wants to coat cheap steel rings with a thin layer of silver, to improve their appearance and prevent the steel from corroding.

   (a)

   What is this process, using electrolysis to coat an object with a thin layer of a different metal, called?

   [1 mark]

   • ADisplacement
   • BThermal decomposition
   • CPhytomining
   • DElectroplating

   (b)

   In the electroplating process described above, at which electrode would the steel ring be placed, so that silver is deposited onto it?

   [1 mark]

   • AThe anode, because silver ions move towards it and are oxidised
   • BNeither electrode; the ring should not be part of the circuit
   • CThe anode, because it repels silver ions
   • DThe cathode, because silver ions move towards it and are reduced

   (c)

   State two reasons why the manufacturer might choose to electroplate the steel rings with silver rather than making them from solid silver.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A cutlery company electroplates steel forks with a thin layer of copper before a final finish is applied, to improve durability.

   (a)

   Which solution would be most appropriate to use as the electrolyte for copper plating?

   [1 mark]

   • ASodium chloride solution
   • BDilute hydrochloric acid with no copper compound
   • CPure water
   • DCopper sulfate solution

   (b)

   For this copper electroplating process to work correctly, what should be used as the anode?

   [1 mark]

   • AAn inert carbon electrode
   • BA piece of aluminium
   • CThe steel fork itself
   • DA pure copper electrode, so that copper dissolves into solution to replace the copper deposited on the fork

   (c)

   Write the half-equation for the reaction occurring at the cathode (the steel fork) during this copper electroplating process, and explain how this deposits a layer of copper onto the fork.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A workshop sets up an electroplating cell to coat an iron bracket with a thin layer of nickel, to prevent it from corroding outdoors.

   (a)

   Describe the set-up needed for this electroplating process, including the electrolyte and the position of the iron bracket in the circuit.

   [3 marks]

   (b)

   Explain, using ideas about ion movement and electron transfer, how the nickel layer forms on the iron bracket, and give two reasons why electroplating is used in this application rather than simply leaving the iron bracket uncoated.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A manufacturer of household taps wants to coat brass fittings with a thin, decorative and protective layer of chromium using electroplating.

   (a)

   Explain, in full, how this electroplating process would be carried out, including the electrolyte used, the roles of the anode and cathode, and the relevant half-equation.

   [6 marks]

   (b)

   Evaluate the benefits of electroplating the brass fittings with chromium compared with leaving the brass uncoated, considering appearance, durability and cost, and suggest one practical factor the manufacturer should control carefully during the process to ensure a good-quality coating.

   [6 marks]

   Total for question 4: 12 marks

End of questions