If E°cell > 0, what can be said about spontaneity and ΔG under standard conditions?

• A. The reaction is spontaneous as written and ΔG° < 0
• B. The reaction is nonspontaneous and ΔG° > 0
• C. Spontaneity depends on temperature
• D. ΔG° = 0 for all cells

Answer: (A)

A positive cell potential means the redox reaction as written has a favorable tendency to proceed in the forward direction under standard conditions. The relationship ΔG° = -n F E°cell links the electrical driving force to Gibbs energy, where n is the number of electrons transferred and F is Faraday’s constant. Since E°cell is positive, the product nF E°cell is positive, so ΔG° becomes negative. A negative ΔG° indicates the reaction is spontaneous in the standard state.

So the forward reaction being spontaneous with ΔG° < 0 is the correct interpretation. The other statements don’t fit: nonspontaneity would require ΔG° > 0, spontaneity depending on temperature would mix in conditions outside the standard state, and ΔG° = 0 would only occur if E°cell were zero.