$E\, = \,1.51 - \,\frac{{0.059}}{5}\log \frac{{[M{n^{2 + }}]}}{{[MnO_4^ - ]\,\,{{[{H^ + }]}^8}}}$
Taking $Mn^{2+}$ and $MnO_4^-$ in standard state i.e.$1\,M,$
$E\, = \,1.51 - \,\frac{{0.059}}{5}\, \times \,\,8\,\,\log \frac{1}{{\,[{H^ + }]}}$$\, = \,1.51 - \,\frac{{0.059}}{5}\, \times \,\,8\, \times \,3 = 1.2268\,\,V$
Hence at this $pH,$ $MnO_4^-$ will oxidise only $Br^-$ and $I^-$ as $SRP$ of $Cl_2/Cl^-$ is $1.36\,V$ which is greater than that for $MnO_4^-$ $/Mn^{2+}$.
$298\,K$ પર પ્રક્રિયા માટે ગિબ્સ મૂક્ત ઊર્જા ફેરફાર $Cu ( s )+ Sn ^{2+}(0.001 \,M ) \rightarrow\,Cu ^{2+}(0.01 M )+ Sn ( s ), x \times 10^{-1}\, kJ \,mol ^{-1} s .$
[આપેલ : $F =96500\,C\,mol ^{-1}$ ] તો $x$ નું મૂલ્ય $\dots\dots$ છે.
$\mathrm{Cr}_2 \mathrm{O}_7{ }^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \mathrm{E}^{\circ}=1.33 \mathrm{~V}$
$\mathrm{Fe}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \mathrm{E}^{\circ}=-0.04 \mathrm{~V}$
$\mathrm{Ni}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{Ni} \mathrm{E}^{\circ}=-0.25 \mathrm{~V}$
$\mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Ag} \mathrm{E}^{\circ}=0.80 \mathrm{~V}$
$\mathrm{Au}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Au} \mathrm{E}^{\circ}=1.40 \mathrm{~V}$
આપેલી ઇલેક્ટ્રોકેમિસ્ટ્રી પ્રતિક્રિયાઓને લઈને, જે ધાતુ(ઓ) આકસ્મિક થશે તેનું ક્રોમિયમ ઓક્સાઇડ અમળમાં $\mathrm{Cr}_2 \mathrm{O}_7{ }^{2-}$ ના મૂળ્ય છે. . . . . .
$Fe_{(aq)}^{3 + } + {e^ - } \to Fe_{(aq)}^{2 + }$ ; ${E^o} = 0.771{\mkern 1mu} \,volts;{\mkern 1mu} $
${\mkern 1mu} {I_{2(g)}} + 2{e^ - } \to 2I_{(aq)}^ - \,;{\mkern 1mu} $ ${E^o} = 0.536{\mkern 1mu} \,volts$
કોષ પક્રિયા $2Fe^{3+}_{(aq)} + 2l^{-}_{(aq)} \rightarrow 2Fe^{2+}_{(aq)} + I_{2(g)}$ માટે $E^o_{cell} = ….$