A technician electrolyses aqueous copper(II) sulfate using inert graphite electrodes. The half-equation at the anode is: 4OH⁻ → O₂ + 2H₂O + 4e⁻. What observation would the technician make at the anode?

Q: How do I try a free WJEC Chemistry question?

Just tap any of the four options on this page — no signup, no card, nothing to install. You'll see the correct answer and a full mark-scheme-style explanation within a second. Each visit shows a fresh randomly-picked question from the live WJEC GCSE Chemistry bank, so you can keep refreshing to try different ones before deciding whether to create a free account for daily access.

Q: Is Kramizo really free for WJEC Chemistry students?

Yes — completely free. Every student gets 45 questions a day on the free plan, across any board and any subject, with no card required and no trial countdown. Kramizo's optional Pro plan removes the daily cap and adds analytics, but the free plan is genuinely free forever. We make money from the small percentage of students who choose to upgrade — not from selling data or ads.

Q: Are the Chemistry questions aligned to the WJEC GCSE syllabus?

Every question is written against the published WJEC GCSE Chemistry syllabus and reviewed for accuracy before being added to the bank. We match the command words (state, describe, explain, evaluate), mark allocations, and difficulty tier you'll see on real WJEC past papers. Explanations are written in the style of official examiner mark schemes so students learn exactly what marks are being awarded for.

Question

A technician electrolyses aqueous copper(II) sulfate using inert graphite electrodes. The half-equation at the anode is: 4OH⁻ → O₂ + 2H₂O + 4e⁻. What observation would the technician make at the anode?

Accepted Answer

Bubbles of gas are produced — Award 1 mark for bubbles of gas (oxygen). The half-equation shows O₂ gas is produced. C is incorrect — brown copper forms at the cathode, not anode. D is incorrect — inert electrodes do not react. B is incorrect — the blue solution is present throughout (from Cu²⁺ ions).

Answer

The electrode disappears

Answer

A blue solution forms

Answer

Bubbles of gas are produced

Answer

A brown coating forms

One real Chemistry question.No signup. 30 seconds.

One real Chemistry question.
No signup. 30 seconds.