\(C{r_2}O_7^{2 - }\, + \,6{e^ - }\, + \,14{H^ + }\, \to 2C{r^{3 + }}\, + \,7{H_2}O\)
Oxidation half reaction :
\(Cr\, \to \,C{r^{3 + }}\, + \,3{e^ - }\)
Overall reaction :
\(C{r_2}O_7^{2 - }\, + \,Cr\, + \,14{H^ + }\, + \,\) \(3{e^ - }\, \to 3C{r^{3 + }}\, + \,7{H_2}O\)
\(3\,F\) of electricity \(=\,3\,moles\) of \(Cr^{3+}\)
\(1\,F\) of electricity \(=\,\frac {3}{3}\,moles\) of \(Cr^{3+}\)
$Pt \left| H _{2}( g , 1 bar )\right| H ^{*}( aq ) \| Cu ^{2+}( aq ) \mid Cu ( s )$
$0.31\,V$ છે. આ એસિડિક દ્રાવણની $pH$ માલુમ પડી. જ્યારે $Cu ^{2+}$ નું સાંદ્રતા $10^{-x} m$ છે.તો $x$ નું મૂલ્ય $\dots\dots$.
(આપેલ: $E _{ Cu ^{2+} / Cu }^{\ominus}=0.34 \,V$ અને $\left.\frac{2.303 RT }{ F }=0.06\, V \right)$
આપેલ :
$F{e^{2 + }} + 2{e^ - } \to Fe;$ ${E^o}_{F{e^{2 + }}/Fe} = - 0.47\,V$
$F{e^{3 + }} + {e^ - } \to F{e^{2 + }};$ ${E^o}_{F{e^{3 + }}/F{e^{2 + }}} = + 0.77\,V$