In the galvanic cell Pt | Fe2+/Fe3+ || Ag+/Ag, how many electrons are transferred in the balanced overall reaction?

• A. Two electrons
• B. Zero electrons
• C. One electron
• D. Three electrons

Answer: (C)

Electrons move from the species being oxidized to the species being reduced in a galvanic cell. Here, Fe2+ is oxidized to Fe3+, releasing one electron. At the same time, Ag+ is reduced to Ag, consuming one electron. Each half-reaction involves exactly one electron, so the same electron travels through the external circuit from the iron side to the silver side. If you write the overall cell reaction by combining the two half-reactions, the electrons cancel, giving Fe2+ + Ag+ → Fe3+ + Ag. The net equation shows no electrons, but the process involves transferring one electron per reaction event.