If standard reduction potential of four electrodes A, B, C, D are +2.5 , V , +3.0 , V , -2.0 , V and -1.5 , V respectively. When is the standard emf of cell maximum?

Step-by-step solution

The standard emf of a cell is given by E^ _ cell = E^ _ cathode - E^ _ anode . To obtain the maximum standard emf, the cathode must have the highest standard reduction potential and the anode must have the lowest standard reduction potential. Given standard reduction potentials are: E^ _ A = +2.5 V E^ _ B = +3.0 V E^ _ C = -2.0 V E^ _ D = -1.5 V The highest reduction potential is for electrode B ( +3.0 V ), so B should act as the cathode. The lowest reduction potential is for electrode C ( -2.0 V ), so C should act