Which statement correctly describes the standard reduction potential?

• A. E° is the intrinsic tendency to lose electrons under standard conditions.
• B. E° is the intrinsic tendency to gain electrons under standard conditions; cell potential is E°cell = E°cathode − E°anode.
• C. E° is the kinetic barrier to electron transfer.
• D. E°cell equals E°anode − E°cathode.

Answer: (B)

The standard reduction potential measures how much a species tends to gain electrons under standard conditions—the more positive the value, the stronger its drive to be reduced. In a galvanic cell, the overall standard potential comes from comparing the cathode’s tendency to gain electrons with the anode’s tendency to lose them, and the correct relation is E°cell = E°cathode − E°anode. This arrangement gives a positive cell potential for spontaneous cells when the cathode’s reduction potential exceeds the anode’s. The other statements misstate what E° measures (tendency to lose electrons would be an oxidation tendency, not the reduction potential), or mix up the concept with a kinetic barrier (activation energy), or give the wrong sign for E°cell.