Electrochemistry - Result Question 44
####46. If $E _{Fe^{2+} / Fe}^{\circ}=-0.441 V$ and $E _{Fe^{\circ} / Fe^{2+}}$ $=+0.771 V$, the standard EMF of the reaction $Fe+2 Fe^{3+} \to 3 Fe^{2+}$ will be
(a) $1.653 V$
(b) $1.212 V$
(c) $0.111 V$
(d) $0.330 V$
[2006]
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Solution:
- (b)
$Fe \longrightarrow Fe^{2+}+2 e^{-} \quad$ [Anode] $\quad E=-0.441 V$
$\xrightarrow{[Fe^{3+}+e^{-} \longrightarrow Fe^{2+}] \times 2[\text{ [Cathode }] E=+0.771 V}$
$Fe+2 Fe^{3+} \longrightarrow 3 Fe^{2+}$
$E _{\text{cell }}^{o}=E _{\text{cathode }}^{o}-E _{\text{Anode }}^{o}$
$=0.771-(-0.441)=0.771+0.441=1.212 V$
