The electrolysis of sodium chloride solution
2 marks · EasyAt the cathode during the electrolysis of sodium chloride solution, two different possible ions could gain electrons. Use the position of sodium and hydrogen in the reactivity series to deduce which ion is discharged.
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Hydrogen ion (H⁺) is discharged because it is lower than sodium in the reactivity series.
Also accept: Hydrogen ions are less reactive than sodium ions so are discharged.
Common mistakes: Sodium is lower; Sodium discharged
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Marking points
M1 · 1 mark · Refers (explicitly or by reasoning) to position in the reactivity series.
A1 · 1 mark · Correctly deduces H⁺ is discharged as it is less reactive (below Na).
Worked solution
Hydrogen is lower in the reactivity series than sodium, so H⁺ ions are discharged at the cathode instead of Na⁺.