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Calculate the standard cell potential (in V) of the cell in which the following reaction takes place: F e 2 +   a q + A g + a q → F e 3 + a q + A g ( s ) Given that E Ag + / A g o = x   V E F e 2 + / F e o = y   V E F e 3 + / F e o = z   V

Options

  1. Ax + 2 y - 3 z
  2. Bx - y
  3. Cx - z
  4. Dx + y - z

Correct answer

A. x + 2 y - 3 z

Step-by-step solution

F e + 2 A + A g + C → F e 3 + + A g E c e l l o = S R P of cathode -   S R P of anode = E A g + | A g o - E F e + 3 | F e + 2 o = x - E F e 3 + | F e + 2 o Since E ° cell is an intensive property, the E ° cell values are not additive by nature. But the standard Gibbs free energy change is an extensive property and hence can be added. (i) F e + 3 → F e + 3 e - → Z = E 1 o ;    Δ G 1 = - 3 × F × z (ii) F e + 2 → F e + 2 e - Y = E 2 o ;   Δ G

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