In an electrolytic cell, explain why metal ions are reduced at the cathode even though the cathode is the negative electrode.
Answer
Because electrons are supplied to the cathode, reducing metal ions to metal; the negative charge attracts positively charged ions, making reduction thermodynamically favourable.
Step-by-step solution
- Recall that electrons flow from the external circuit into the cathode, giving it negative charge.
- Positively charged metal ions are attracted to the negatively charged cathode surface.
- At the cathode electrons combine with the metal ions, reducing them to neutral metal atoms.
- Hence the metal is deposited (reduced) at the cathode, not oxidised.
- This process occurs despite the cathode’s negative polarity because the driving force is the electron supply from the external circuit, not the electrode potential alone.
Common mistake: Thinking reduction occurs at positive electrode
Concept tested: Electrolysis: cathodic reduction
Published · How this solution was prepared and checked
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