Question

Standard electrode potential data are useful for understanding the suitability of an oxidant in a redox titration. Some halt"-cell reactions and their standard potentials are given below:

Identify ihe incorrect statement regarding the quantitative estimation of gaseous Fe(NO₃)₂ 

(a) MnO₄^- can be used in aqueous HCI 

(b) Cr₂O^2-₇ can be used in aqueous HCI 

(c) MnO₄^- can be used in aqueous H₂SO₄

(d) Cr₂O^2-₇ can be used in aqueous H₂SO₄

Answer 1

The correct option (a) MnO₄^- can be used in aqueous HCI 

Explanation:

The reaction between MnO^-₄ and HCI may be represented as follows :

E° cell is positive, hence ΔG° is negative. Thus, above celi reaction is feasible but MnO^-₄ ion can oxidise, Fe²⁺ to Fe³⁺ and Cl^- to Cl₂ in aqueous medium also. Therefore, for quantitative estimation of aqueous Fe (NO₃)₂ it is not a suitable reagent.