The electrolysis of copper(ii) sulfate solution using inert electrodes
2 marks · EasyDescribe how a sample of copper(II) sulfate solution would be different after it is electrolysed for a long time using inert electrodes.
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The blue color fades and the solution becomes colorless; the solution turns into dilute sulfuric acid.
Must show: Change in color (blue to colorless), Change in composition (forms dilute sulfuric acid)
Also accept: Copper ions are removed and solution fades.; Solution becomes acidic because sulfuric acid forms.
Common mistakes: No mention of color change; No mention of acid formation
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Marking points
B1 · 1 mark · States/deduces the color fades/solution becomes colorless as copper(II) ions are removed.
B1 · 1 mark · Identifies that the remaining solution contains dilute sulfuric acid (or says solution becomes acidic).
Worked solution
After prolonged electrolysis, the blue color of the solution fades as copper(II) ions are removed, and the solution turns into dilute sulfuric acid.