Question

Standard electrode potential data are useful for understanding the suitability of an oxidant in a redox titration. Some half cell reactions and their standard potentials are given below :
$MnO_4^- (aq.) + 8H^+ (aq.) + 5e^- \rightarrow Mn^{2+}(aq.) + 4H_2O(l)$ E° = 1.51 V
$Cr_2O_7^{2-} (aq.) + 14H^+ (aq.) + 6e^- \rightarrow 2Cr^{3+} (aq.) + 7H_2O(l)$ E° = 1.38 V
$Fe^{3+} (aq.) + e^- \rightarrow Fe^{2+} (aq.)$ E° = 0.77 V
$Cl_2 (g) + 2e^- \rightarrow 2Cl^- (aq.)$ E° = 1.40 V
Identify the only incorrect statement regarding the quantitative estimation of aqueous Fe(NO₃)₂
(a) $MnO_4^-$ can be used in aqueous HCl
(b) $Cr_2O_7^{2-}$ can be used in aqueous HCl
(c) $MnO_4^-$ can be used in aqueous H₂SO₄
(d) $Cr_2O_7^{2-}$ can be used in aqueous H₂SO₄

Answer 1

(a) option is correct