Which statement correctly describes a galvanic cell with a positive standard cell potential E°cell?

Which statement correctly describes a galvanic cell with a positive standard cell potential E°cell?

• A. The reaction is spontaneous under standard conditions.
• B. The reaction is nonspontaneous under standard conditions.
• C. The reaction is at equilibrium under standard conditions.
• D. Spontaneity cannot be predicted from E°cell.

Answer: (A)

A positive standard cell potential means the redox reaction as written tends to proceed on its own under standard conditions. This happens because the free energy change is ΔG° = -nF E°cell; with E°cell positive, ΔG° becomes negative, so the reaction is spontaneous. In a galvanic cell, E°cell is positive when the cathode has the larger reduction potential and the anode the smaller, giving E°cell = E°cathode − E°anode > 0. Under standard conditions (1 M solutions, 1 atm gases, 25°C), this positive E°cell indicates the cell will generate electrical energy spontaneously. If E°cell were negative, the process would be nonspontaneous under standard conditions; if it were zero, the system would be at equilibrium.

A positive standard cell potential means the redox reaction as written tends to proceed on its own under standard conditions. This happens because the free energy change is ΔG° = -nF E°cell; with E°cell positive, ΔG° becomes negative, so the reaction is spontaneous. In a galvanic cell, E°cell is positive when the cathode has the larger reduction potential and the anode the smaller, giving E°cell = E°cathode − E°anode > 0. Under standard conditions (1 M solutions, 1 atm gases, 25°C), this positive E°cell indicates the cell will generate electrical energy spontaneously. If E°cell were negative, the process would be nonspontaneous under standard conditions; if it were zero, the system would be at equilibrium.