Electroplating — Past Paper Exam
Setup, Purpose & Observations · 15 Questions
Examiner's Note: Electroplating questions appear in Paper 4 (Theory) and Paper 6 (Practical). You must know the exact role of each component, the half-equations at both electrodes, and how mass changes. Common marks are lost by confusing anode/cathode or writing vague electrolyte descriptions.
Section A
5 Qs
Purpose
Section B
5 Qs
Setup & Diagram
Section C
5 Qs
Observations
State two reasons why metal objects are electroplated.
Give one example of an industrial use of electroplating and explain why it is used in that context.
State one reason why jewellery is often silver-plated rather than made entirely of silver.
Explain, in terms of ions and electrons, what happens at the cathode during electroplating.
Explain, in terms of ions and electrons, what happens at the anode during electroplating with a copper anode.
Draw and label the apparatus used to electroplate a steel ring with copper. Your diagram must show: the anode, cathode, electrolyte, power supply, and the direction of conventional current.
Model Diagram — Electroplating Setup
What material should the anode be made of when electroplating an object with copper?
What should the electrolyte be when electroplating with copper? Give its name and state why it must be soluble.
Explain why it is important to clean the surface of the steel ring before electroplating.
A student increases the current during electroplating. State and explain the effect on the quality of the copper coating.
What happens to the mass of the copper anode during electroplating? Explain why.
What happens to the mass of the cathode (steel ring) during electroplating? Explain why.
Predict what would happen to the concentration of the copper(II) sulfate electrolyte over time if a pure copper anode is used. Explain your answer.
A steel spoon is electroplated with silver. The anode is made of pure silver and the electrolyte is silver nitrate solution. (a) Write the half-equation for the reaction at the cathode. (b) Write the half-equation for the reaction at the anode. (c) State the type of reaction occurring at each electrode.
A student electroplates a copper coin with nickel. The mass of the coin before plating is 3.20 g. After plating for 20 minutes, the mass is 3.52 g. (a) Calculate the mass of nickel deposited. (b) The student claims the anode must have lost exactly the same mass. Evaluate this claim.
⚡ Core Electroplating Summary — Must Know
The Golden Rules
- • Cathode = object being plated → REDUCTION (Cu²⁺ + 2e⁻ → Cu)
- • Anode = plating metal (e.g. pure copper) → OXIDATION (Cu → Cu²⁺ + 2e⁻)
- • Electrolyte = soluble salt of the plating metal (e.g. CuSO₄ aq)
- • Anode loses mass; cathode gains mass
- • Electrolyte concentration stays constant (with active anode)
Top 3 Examiner Traps
- 1. Writing "the anode gains mass" — it loses mass
- 2. Using "salt solution" as the electrolyte — must name it: copper(II) sulfate
- 3. Connecting the object to the + terminal — it must be the cathode (−)
Cambridge IGCSE Chemistry 0620 · Topic 4.1.6 Electroplating · © GenZStudi
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