An electrochemical cell comprises two half-cells joined by a wire and a salt bridge. Which statement best describes its function?

• A. A device that stores energy without any chemical reaction
• B. A system with no net electron transfer
• C. A device that generates a current from a redox reaction between two half-cells
• D. A device that consumes energy to move electrons against their potential

Answer: (C)

This setup tests how a galvanic (voltaic) cell converts chemical energy into electrical energy through a spontaneous redox reaction in two half-cells. The wire lets electrons flow from the electrode where oxidation occurs (anode) to the electrode where reduction happens (cathode), producing an electric current that can drive external work. The salt bridge maintains electrical neutrality by allowing ions to move between half-cells, so the reaction can continue without building up charge that would stop it. Because the redox reaction is spontaneous, the cell generates current rather than requiring input energy. The other statements don’t fit: there is indeed electron transfer and chemical reaction, and moving electrons against their potential would require external power, which describes an electrolytic cell rather than this setup.