O-LevelChemistryElectrolysis5070/11 · May/June 2023 · Q111 Mark
Concentrated aqueous sodium chloride is electrolysed using inert electrodes. Which row shows what happens in this electrolysis and why it happens?
Achange occurring: oxygen is discharged at the anode, explanation: OH⁻(aq) loses electrons more easily than Cl⁻(aq)
Bchange occurring: during electrolysis the pH of the electrolyte increases, explanation: the electrolysis in aqueous solution involves the reduction of H⁺(aq) ions
Cchange occurring: solid sodium is produced at the cathode, explanation: Na⁺(aq) is present in aqueous solution
Dchange occurring: the products stay the same if the aqueous sodium chloride is replaced by molten sodium chloride, explanation: Na⁺ and Cl⁻ are present in both molten and aqueous sodium chloride
✓ Correct answer
B: change occurring: during electrolysis the pH of the electrolyte increases, explanation: the electrolysis in aqueous solution involves the reduction of H⁺(aq) ions
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