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Given : E _ Fe ³⁺ / Fe ^ =-0.036 ~V , E _ Fe ²⁺ / Fe ^ =-0.439 ~V . The value of standard electrode potential for the change, Fe _ ( aq ) ³⁺+ e ⁻ Fe ²⁺( aq ) will be :

Options

  1. A-0.072 ~V
  2. B0.385 ~V
  3. C0.770 ~V
  4. D-0.270

Correct answer

C. 0.770 ~V

Step-by-step solution

aligned & Fe ³⁺+3 e ⁻ Fe ; E ^ =-0.036 ~V & G ₁^ =- nFE ^ =-3 ~F (-0.036) & =+0.108 ~F & Also Fe ²⁺+2 e ⁻ Fe ; E ^ =-0.439 ~V & G ₂^ =- nFE ^ & =-2 ~F (-0.439) & =0.878 ~F & To find E ^ for Fe _ ( aq ) ³⁺+ e ⁻ Fe ²⁺( aq ) & G ^ =- nFE ^ =-1 FE & G ^ = G ₁^ - G ₂^ & G ^ =0.108 ~F -0.878 ~F & - FE ^ =+0.108 ~F -0.878 ~F & E ^ =0.878-0.108 & =0.77 ~V aligned

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