What this practice covers
These questions are drawn from past CIE 9701 Chemistry papers and filtered to electrochemistry. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on electrochemistry, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Saying oxidation happens at the cathode. Reduction is at the cathode, in electrolysis and in a cell.
- Predicting oxygen at the anode from a concentrated halide solution. Concentration overrides the electrode potential there.
- Leaving the time in minutes in Q = It.
- Forgetting to divide the moles of electrons by the number in the half-equation, so a copper mass comes out twice too large.
- Multiplying an E° value when a half-equation is multiplied to balance electrons. E° is intensive and never scales.
- Adding two E° values instead of subtracting.
- Saying the standard hydrogen electrode has a measured potential of zero. It is defined as zero.
- Leaving out the platinum black, the 101 kPa or the 1.00 mol dm⁻³ from a description of the hydrogen electrode.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Electrochemistry revision notes.