In a classic Daniell cell, which electrode serves as the anode and which serves as the cathode during spontaneous operation?

• A. Zinc electrode is the anode; copper electrode is the cathode
• B. Copper electrode is the anode; zinc electrode is the cathode
• C. Both electrodes act as anodes
• D. Neither electrode participates in redox

Answer: (A)

In a spontaneous galvanic cell, oxidation occurs at the anode and reduction occurs at the cathode, with electrons flowing from the anode to the cathode through the external circuit. In the Daniell cell, zinc metal is oxidized at the zinc electrode: Zn(s) → Zn2+ + 2e−. This makes the zinc electrode the anode. The electrons then move to the copper electrode, where copper(II) ions are reduced to copper metal: Cu2+ + 2e− → Cu(s). This places the copper electrode at the cathode. The overall reaction is Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s), and the positive cell potential confirms spontaneity.