The electrolysis of some other solutions using inert electrodes
2 marks · HardAn aqueous solution of zinc sulfate is electrolysed using inert electrodes.
State whether hydrogen or zinc is produced at the cathode. Explain your answer using the reactivity series.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Hydrogen is produced at the cathode because zinc is above hydrogen in the reactivity series.
Also accept: Hydrogen because it is less reactive than zinc.; Hydrogen because zinc ions are less easily reduced than hydrogen ions.
Common mistakes: Zinc is produced at the cathode because it is a metal.; Both zinc and hydrogen are produced.
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Hydrogen identified as the cathode product.
B2 · 1 mark · Explanation clearly refers to zinc being above hydrogen in the reactivity series (or relevant statement about relative reactivities).
Worked solution
At the cathode, either Zn²⁺ ions or H⁺ ions can be reduced.
Zinc is above hydrogen in the reactivity series, so hydrogen ions are reduced instead.
Hydrogen is produced at the cathode.