Question

What is the value for Ecell for the reaction shown below if each one of the dissolved species has a concentration of 0.1 M?

2 Fe3+ (aq) + 2 I-(aq) → 2 Fe2+(aq) + I2(s)

a) -0.35 V

b) -0.29 V

c) +0.11 V

d) +0.17 V

Answer 1

2I^- (aq) + 2e^- --------------------> I2(s)                      E0 = -0.54v

2Fe^3+ (aq) + 2e^- -------------> 2Fe^2+ (aq)         E0   = 0.77v

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2I^- (aq) + 2Fe^3+ (aq) --------------> I2(s) + 2Fe^2+ (aq)        E0 cell = 0.23v

     n = 2

Ecell    = E0cell - 0.0592/n log[Fe^2+]^2/[I^-]^2[Fe^3+]^2

           = 0.23 - 0.0592/2 log(0.1)^2/(0.1)^2*(0.1)^2

          =0.23-0.0296log1/(0.1)^2

        = 0.23-0.0296*2

     = 0.17v

d) +0.17 V >>>>answer