Reduction occurs at which electrode in an electrochemical cell?

• A. Cathode
• B. Anode
• C. Electrolyte
• D. Electrode

Answer: (A)

The key idea is that reduction—the gain of electrons—occurs at the cathode. In an electrochemical cell, electrons flow from the anode to the cathode through the external circuit. The cathode is the electrode that accepts those electrons from the circuit, so species in the electrolyte at that electrode are reduced (for example, metal ions gain electrons and deposit as metal on the electrode). The electrolyte itself is the ionic medium, not an electrode, so it doesn’t undergo reduction at an electrode surface. A concrete picture is a Zn–Cu cell: Zn is oxidized at the anode, electrons travel to the copper electrode, and Cu2+ in solution gains those electrons to deposit as Cu on the cathode.