The electrolysis of copper(ii) sulfate solution using inert electrodes
3 marks · EasyThe table below shows the ions present in copper(II) sulfate solution before and after electrolysis with inert electrodes.
| Ion | Before electrolysis | After prolonged electrolysis |
|---|---|---|
| Cu^{2+} | Present | Absent |
| SO_4^{2-} | Present | Present |
| H^+ | Present | Present |
| OH^- | Present | Absent |
From the table, state which ion is responsible for the product formed at the cathode, and name the product.
From the table, state which ion is responsible for the product formed at the anode, and name the product.
Using your answers, give the overall effect of electrolysis on the copper(II) sulfate solution.
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
(a) Cu^{2+}; copper · must show States Cu^{2+}, Names copper
(b) OH^-; oxygen · must show States OH^-, Names oxygen
(c) Copper ions are removed and oxygen is formed, leaving a solution of sulfuric acid. · must show Copper ions removal, Oxygen formation, Sulfuric acid formation
Common mistakes: Mixing up cathode/anode
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Marking points
B1 · 1 mark · States Cu^{2+} is responsible for the cathode product and names copper.
B1 · 1 mark · States OH^- is responsible for the anode product and names oxygen.
B1 · 1 mark · Correctly describes the overall effect (removal of copper ions, oxygen produced, sulfuric acid left).
Worked solution
a) Cu^{2+} is responsible for the product at the cathode, which is copper metal.
b) OH^- is responsible for the product at the anode, which is oxygen gas.
c) Copper(II) ions are removed, oxygen is produced, and the remaining solution becomes sulfuric acid.