Bioleaching produces a solution containing copper ions, Cu2+\mathrm{Cu^{2+}}Cu2+. Copper metal can be obtained from the solution by electrolysis or by adding scrap iron.
Which statement is correct?
In electrolysis, copper ions gain electrons at the negative electrode.
In electrolysis, copper forms at the positive electrode, because copper ions are positive.
When scrap iron is added, iron atoms gain electrons to form iron ions.
When scrap iron is added, copper ions are oxidised to form copper atoms.
61 exam-style questions on OCR GCSE Chemistry 6.1 Improving processes and products, covering 6.1.1 Extracting metals industrially and by electrolysis, 6.1.2 Life cycle assessment and recycling, 6.1.3 Biological methods of metal extraction, 6.1.4 The Haber process and the production of fertilisers, 6.1.5 Alloys and their uses, 6.1.6 Corrosion and its prevention, 6.1.7 Comparing and selecting materials, and 6.1.8 Industrial conditions, rate and position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.