Standard Electrode Potential and Cell EMF

List the given reduction potentials. Choose the larger value as cathode. Choose the smaller value as anode. Substitute directly into E degree cell = E degree cathode - E degree anode. Interpret a positive value as feasible for a galvanic cell.

A separate diagram is not essential here because the concept is mainly sign and formula based. A small comparison table of anode, cathode, oxidation, reduction, and potential sign is useful for revision.

A realistic error is calculating -2.37 - 0.80 = -3.17 V for Mg-Ag cell by subtracting in the wrong order.

Standard electrode potential is the potential of an electrode measured under standard conditions relative to the standard hydrogen electrode, whose potential is assigned zero volts.

Standard electrode potential is the potential of an electrode measured under standard conditions relative to the standard hydrogen electrode, whose potential is assigned zero volts. Key formula: E degree cell = E degree cathode - E degree anode. Under standard conditions, solute concentration is 1 mol L-1, gas pressure is 1 bar, and temperature is usually taken as 298 K in numerical questions unless stated otherwise. If E degree of Cu2+/Cu = +0.34 V and E degree of Zn2+/Zn = -0.76 V, then E degree cell = 0.34 - (-0.76) = 1.10 V for the Daniell cell.

Electrode potential values in the CBSE table are usually standard reduction potentials. A more positive reduction potential means the species has a greater tendency to get reduced. For a galvanic cell, the cathode has the higher reduction potential and the anode has the lower reduction potential. The standard EMF of the cell is calculated as the standard reduction potential of cathode minus that of anode. The sign of EMF indicates whether the cell reaction is spontaneous as written. Key formula: E degree cell = E degree cathode - E degree anode. Under standard conditions, solute concentration is 1 mol L-1, gas pressure is 1 bar, and temperature is usually taken as 298 K in numerical questions unless stated otherwise. Given Mg2+/Mg = -2.37 V and Ag+/Ag = +0.80 V, silver ion has the higher reduction potential, so Ag electrode is cathode and Mg is anode. E degree cell = 0.80 - (-2.37) = 3.17 V. The positive value shows that the reaction is spontaneous in this direction. CBSE questions may ask for EMF calculation, feasibility of a redox reaction, strongest oxidising agent, strongest reducing agent, or correct cell representation using electrode potential data. A realistic error is calculating -2.37 - 0.80 = -3.17 V for Mg-Ag cell by subtracting in the wrong order.