Question 17 of 170

Standard potential data are usefull for understanding the suitability of an oxident in a redox titration. Some half cell reactions and their standard potentials are given ahead;

$$\begin{gathered} {\mathrm{MnO}}_4^{-}\left(\mathrm{aq}\right) + 8{\mathrm{H}}^{+}\left(\mathrm{aq}\right) + 5{\mathrm{e}}^{-} \stackrel{ }{\to }{\mathrm{Mn}}^{2+}\left(\mathrm{aq}\right) + 4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right); E°=1.51\mathrm{V} \\ {\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}\left(\mathrm{aq}\right) +\hspace{0.17em}14{\mathrm{H}}^{+}\left(\mathrm{aq}\right) + 6{\mathrm{e}}^{-} \stackrel{ }{\to }+2{\mathrm{Cr}}^{3+} \left(\mathrm{aq}\right) + 7{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right);E°=1.38\mathrm{V} \\ {\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right) + {\mathrm{e}}^{-} \stackrel{ }{\to }{\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right); E°=0.77\mathrm{V} \\ {\mathrm{Cl}}_2\left(\mathrm{g}\right) +2{\mathrm{e}}^{-} \stackrel{ }{\to }2{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right); E°=1.40\mathrm{V} \end{gathered}$$

Identify the only incorrect statement regarding the quantitative estimation of aqueous Fe(NO₃)₂:

(a) ${\mathrm{MnO}}_4^{-}$ can be used in aqueous HCl

(b) ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$can be used in aqueous HCl

(c) ${\mathrm{MnO}}_4^{-}$can be used in aqueous H₂SO₄

(d) ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$can be used in aqueous H₂SO₄