Question

What is the electrode potential of $Fe^{3+}/ Fe$ electrode in which concentration of $Fe^{3+}$ ions is 0.1 M. Given $E^\circ Fe^{3+}/Fe = + 0.771 V$

• A. +0.79 V
• B. +0.75 V
• C. 1.50 V
• D. +1.0 V

Answer 1

Answer: (B)

+0.75 V

Answer 2

$Fe^{3+} + 3e^- {->} Fe$ $E = E^0 - \frac{0.059}{n}\,log \frac{[Fe]}{[Fe^{3+}]}$ $= + 0.771 - \frac{0.059}{n} \,log \frac{1}{0.1}$ $= + 0.75\,V$