An acidic solution containing Fe²⁺ ions is analyzed by titration with 0.0200 M KMnO₄
CHEMISTRY · Multi-part · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
An acidic solution containing Fe²⁺ ions is analyzed by titration with 0.0200 M KMnO₄. In acidic medium the reaction that occurs is represented by the balanced ionic equation:
5 Fe²⁺(aq) + MnO₄⁻(aq) + 8 H⁺(aq) → 5 Fe³⁺(aq) + Mn²⁺(aq) + 4 H₂O(l)
A 10.00 mL aliquot of the Fe²⁺ solution requires 14.26 mL of the permanganate solution to reach the end point, signaled by the first persistent pink color.
(a) Calculate the molarity of Fe²⁺ in the original solution.
(b) Determine the mass of elemental iron, in grams per liter of the Fe²⁺ solution, corresponding to the molarity found in part (a).
(c) Suppose the concentration of the KMnO₄ standard solution is actually 0.0196 M rather than 0.0200 M. Discuss quantitatively how this systematic error would affect the calculated molarity of Fe²⁺.
(d) Propose one procedural modification that would decrease the relative uncertainty of the titration result, and justify how it accomplishes this.