Question

Calculate the potential for the following redox reaction:

2Fe3+(aq) + Sn2+(aq) ↔ Sn4+(aq) + 2Fe2+(aq)

for a solution in which [Fe3+] = 0.050 M, [Fe2+] = 0.030 M, [Sn2+] = 0.015 M and

[Sn4+] = 0.020 M. Fe3+/ Fe2+ = 0.771 V; Sn4+/ Sn2+ = 0.154 V.

Also show the balanced oxidation and reduction half‐reactions.

Answer 1

Fe³⁺ + e^- = Fe²⁺

Sn⁴⁺ + 2e^- = Sn²⁺

E = E^o + (RT / zF)ln(ox / red)

E_{Fe3+/ Fe2+} = 0.784 V

E_{Sn4+/ Sn2+} = 0.161 V

E = E_{Fe3+/ Fe2+} - E_{Sn4+/ Sn2+} = 0.784 - 0.161 = 0.623 V.