E°cell from reduction potentials

Worked example

The cathode half-cell has E° = 1.09 V and the anode half-cell E° = −0.28 V (both reduction potentials). Find E°cell.

1. 1. Cell potential from half-cells: solve for E°cell

   $E^\circ_\mathrm{cell} = E^\circ_\mathrm{cathode} - E^\circ_\mathrm{anode}$

   = 1.370 V

Answer: E°cell = 1.37 V

Method

E°cell = E°(cathode) − E°(anode), using reduction potentials for both.

Common mistakes

• Both values are reduction potentials: subtract, E°cell = E°(cathode) − E°(anode). Do not flip and add.

Formulas used

• Cell potential from half-cells

  $E^\circ_\mathrm{cell} = E^\circ_\mathrm{cathode} - E^\circ_\mathrm{anode}$

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