Copper Sulfate Electrolysis
Comparing inert vs. active electrodes · Observations · Half-equations · Purification
Section Guide
Section A (Q1–5): Graphite/inert electrodes — products, colour change, half-equations
Section B (Q6–10): Active copper electrodes — observations, why blue stays, mass changes
Section C (Q11–15): Industrial applications — purification, electroplating, diagram drawing
Copper(II) sulfate solution is electrolysed using graphite electrodes. State the product formed at the anode.
State the product formed at the cathode when copper(II) sulfate solution is electrolysed using graphite electrodes.
During electrolysis of copper(II) sulfate using graphite electrodes, the blue colour of the solution gradually fades. Explain why.
Write the half-equation for the reaction occurring at the cathode during electrolysis of copper(II) sulfate solution using graphite electrodes.
Write the half-equation for the reaction occurring at the anode during electrolysis of copper(II) sulfate solution using graphite electrodes.
Copper(II) sulfate solution is electrolysed using copper electrodes. State the observation at the anode.
State the observation at the cathode when copper(II) sulfate solution is electrolysed using copper electrodes.
When copper electrodes are used to electrolyse copper(II) sulfate solution, the blue colour of the solution remains unchanged throughout. Explain why.
Write the half-equation for the reaction at the copper anode during electrolysis of copper(II) sulfate solution.
Compare the changes in mass of the anode and cathode when copper electrodes are used to electrolyse copper(II) sulfate solution. Explain your answer.
In the electrolytic purification of copper, state what material should be used for the anode.
In the electrolytic purification of copper, state what material should be used as the cathode.
Explain what happens to the impurities present in the impure copper anode during electrolytic purification.
Electroplating uses the same principle as copper purification. State TWO conditions required for a metal object to be successfully electroplated with copper.
[DRAWING + EXPLAIN] Draw and label the apparatus used to purify a lump of impure copper by electrolysis. Include labels for: anode, cathode, electrolyte, power supply, and direction of electron flow. Explain what happens at each electrode. [6 marks]
[ Diagram will appear in the answer ]
🔑 Golden Keywords — Electrolysis
Discharged
ions removed at electrode
Oxidation
loss of electrons (anode)
Reduction
gain of electrons (cathode)
Electrolyte
ionic compound in solution/molten
Anode sludge
less reactive impurities settle
Preferential discharge
Cu²⁺ deposited over H⁺
⚠️ Top 3 Examiner Traps
1. Saying anode dissolves with inert electrodes — only happens with active copper anodes.
2. Forgetting that blue colour fades with graphite but stays constant with copper electrodes.
3. Placing impure copper at the cathode in purification diagrams — it must be at the anode.
Sign In to Keep Going
You've reached the end of the free preview. Sign in — and upgrade to Plus or Pro — to keep going with Chemistry.
Full Access
Unlock all 320 lessons