Question

what will the oxidation potential of a ferrous-ferric system in which a ratio (Fe⁺⁺)/(Fe⁺⁺⁺) is 10

Answer 1

Answer on Question #70565 – Chemistry – Other

Task:

What will the oxidation potential of a ferrous-ferric system in which a ratio $(\mathrm{Fe}^{++}) / (\mathrm{Fe}^{+++})$ is 10?

Solution:

Iron (II) ions are easily oxidized to iron (III) ions, and iron (III) ions are easily reduced to iron (II) ions. The equilibrium we are interested in this time is:

$$Fe^{3+} + e = Fe^{2+}, \quad (n = 1), \quad E^0 = 0.771\,V.$$

Nernst equation for ferrous-ferric system:

$$\begin{array}{l} E = E^0 - \frac{RT}{nF} \ln \left(\frac{a_{red}}{a_{ox}}\right); \\ E = E^0 - \frac{0.0592}{n} \lg \left(\frac{[Fe^{2+}]}{[Fe^{3+}]}\right); \\ E = 0.771\,V - \frac{0.0592}{1} \lg (10) = 0.7118\,V \approx 0.712\,V. \end{array}$$

Answer: $E = 0.712\,V$

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