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The standard electrode potentials, E 0 of F e 3 + / F e 2 + and F e 2 + / F e at 300 K are +0.77 V and -0.44 V, respectively. The E 0 of Fe 3 + /Fe at the same temperature is

Options

  1. A1.21 V
  2. B0.33 V
  3. C-0.036 V
  4. D0.036

Correct answer

C. -0.036 V

Step-by-step solution

Fe 3+ + e − → Fe 2+ ; ΔG 1 o = − 1 × F × 0 .77 Fe 2+ + 2 e − → Fe; ΔG 2 o = 2 × F × 0 .44 Fe 3+ + 3 e − → Fe; ΔG 3 o = − 3 × F × E o =0 .11 V ∴   E o = − 0.11 3 = − 0.036   V

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