Which type of electrochemical cell generates electrical energy from a spontaneous redox reaction?

• A. Electrolytic cell
• B. Fuel cell
• C. Photoelectric cell
• D. Galvanic cell

Answer: (D)

A galvanic cell is designed to turn the energy released by a spontaneous redox reaction into electrical energy. In this setup, oxidation happens at the anode and reduction at the cathode, with electrons flowing through an external circuit from the anode to the cathode. The reaction has a negative Gibbs free energy change (ΔG < 0) and a positive cell potential (Ecell > 0), so electricity is produced rather than consumed. A salt bridge or porous barrier keeps the charges balanced as ions move to maintain neutrality.

Electrolytic cells, on the other hand, require external electrical energy to drive a non-spontaneous redox reaction, so they do not generate energy. Fuel cells are a type of galvanic cell that continuously supply reactants, but they still operate on spontaneous redox chemistry. Photoelectric cells use light to drive electron flow rather than spontaneous redox chemistry.