Electrode Potential

Q. Standard electrode potential data are useful for understanding the suitability of an oxidant in a redox Titration. Some half – cell reactions and their standard potential are given below:
$Mn{O}_4^{-}\left(aq\right)+8H^{+}\left(aq\right)+5e^{-}\to M{n}^{2+}\left(aq\right)+4H_{2}O\left(I\right);E^{\circ }=1.51V$
$C{r}_2{O}_7^{2-}\left(aq\right)+14H^{+}\left(aq\right)+6e^{-}\to 2C{r}^{3+}\left(aq\right)+7H_{2}O\left(I\right);E^{\circ }=1.38V$
$F{e}^{3+}\left(aq\right)+e^{-}\to F{e}^{2+}\left(aq\right);E^{\circ }=0.77V$
$C{l}_2\left(g\right)+2e^{-}\to 2C{l}^{-}\left(aq\right);E^{\circ }=1.40V$

Identify the only incorrect statement regarding the quantitative estimation of aqueous $Fe(N{O}_3{)}_2$.

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Q. While $F{e}^{3+}$ is stable, $M{n}^{3+}$ is not stabe in acid solution because:
$(M{n}^{3+}+e^{-}\to M{n}^{2+},E^{\circ }=1.5V;O_2+4H^{+}+4e^{-}\to 2H_{2}O,E^{\circ }=+1.23V;F{e}^{3+}+e^{-}\to F{e}^{2+},E^{\circ }=0.77V)$

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Q. Given below are the half-cell reaction:
$M{n}^{2+}+2e^{\ominus }\to Mn;E^{\ominus }=-1.18V$
$2(M{n}^{3+}+e^{\ominus }\to M{n}^{2+};E^{\ominus }=+1.51V$

The $E^{\ominus }$ for $3M{n}^{2+}\to Mn+2M{n}^{3+}$ will be:
(IIT-JEE 2014)

1. (a) -0.33 V; the reaction will not occur
2. (b) -0.33 V; the reaction will occur
3. (c) -2.69 V; the reaction will not occur
4. (d) -2.69 V; the reaction will occur

Q. The standard reduction potential at ${25}^{o}C$ of $L{i}^{+}/Li,B{a}^{2+}/Ba,N{a}^{+}/NaandM{g}^{2+}/Mg$ are $-3.03,-2.73,-2.71$ and $-2.37$ respectively. Which one of the following is the strongest oxidising agent ?

1. $N{a}^{+}$
2. $L{i}^{+}$
3. $B{a}^{2+}$
4. $M{g}^{2+}$