Question

Use the data of below and find out the most stable oxidised species.
$E^{\circ}_{Cr_2O^{2-}_{7}/Cr^{3+}}=1.33\,V$ ; $\,E^{\circ}_{Cl_2/Cl^{-}}=1.36\,V$
$E^{\circ}_{MnO^{-}_{4}/Mn^{2+}}=1.51\,V$ ; $\, E^{\circ}_{Cr^{3+}/Cr}=-0.74\,V$

• A. $Cr^{3+}$
• B. $MnO^-_4$
• C. $Cr_2O^{2-}_7$
• D. $Mn^{2+}$

Answer 1

Answer: (A)

$E^{\circ}_{Cr^{3+}/Cr}$ has lowest reduction potential hence, $Cr^{3+}$ is the most stable oxidised species.