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:
MnO4–(aq)

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:
MnO4–(aq) + 8H+(aq) + 5e– $\rightarrow$ Mn2+(aq) + 4H2O(l); E° = 1.51 V
Cr2O7^2–(aq) + 14H+(aq) + 6e– $\rightarrow$ 2Cr3+(aq) + 7H2O(l); E° = 1.38 V
Fe3+(aq) + e– $\rightarrow$ Fe2+(aq); E° = 0.77 V
Cl2 (g) + 2e– $\rightarrow$ 2Cl– (aq); E° = 1.40 V
Identify the only incorrect statement regarding the quantitative estimation of aqueous Fe(NO3)2

Prashant Kotian · Accepted Answer

Correct answer: A. To titrate Fe2+, the oxidant must not oxidize the acid medium. MnO4– (1.51 V) is a stronger oxidizing agent than Cl2 (1.40 V), so it will undesirably oxidize Cl– from HCl to Cl2 gas. Cr2O7^2– (1.38 V) is weaker than Cl2 and will not oxidize Cl–. Thus, MnO4– cannot be used in aqueous HCl.

💡 Solution & Explanation

Practice 22,000+ questions like this