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A galvanic cell which makes use of the following reaction at 298K. $Cr_2O_7^{2-}+14H^++6Fe^{2+}\rightarrow 2Cr^{3+}+6Fe^{3+}+7H_2O$.Given : $E^{\large\circ}(Cr_2O_7^{2-},H^+,Cr^{3+}|Pt)=1.33V;E^{\large\circ}(Fe^{3+},Fe^{2+}|Pt)=0.77V$.Upon discharge of the cell for 80 min at one ampere,the anode was found to have decreased in mass by

$\begin{array}{1 1}5.4g\\10.8g\\8.2g\\\text{zero}\end{array} $

1 Answer

Answer : zero
Since the reaction at anode is $Fe^{2+}\rightarrow Fe^{3+}+e^-$ and both $Fe^{2+}$ and $Fe^{3+}$ appear in the solution,there will be no change in the mass of anode which is inert electrode.
answered Jul 21, 2014 by sreemathi.v

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