Fe²⁺(aq)reacts with MnO₄^-(aq)ion in acidic solution to yield Fe³⁺(aq)ions and Mn²⁺(aq)ions. 5Fe²⁺(aq)+ MnO₄^-(aq)+ 8H⁺ $\rarr$ 5Fe³⁺(aq)+ Mn²⁺(aq)+ 4H₂O Melanterite is a greenish mineral, and can be found on the walls of mines. A sample of melanterite, FeSO₄·7H₂O, was analyzed for purity using this reaction by titration of an aqueous solution of the sample. One such sample required 56.15 mL of 0.01301 M permanganate solution to completely titrate all the iron in the sample by the reaction shown above. How much did the sample weigh, if it was in fact pure melanterite? Hint: Watch your units carefully at each step of the problem.

Question

Quizplus · Accepted Answer

The correct answer is A.The balanced chemical equation is:5Fe2+(aq) + MnO4-(aq) + 8H+(aq) → 5Fe3+(aq) + Mn2+(aq) + 4H2OThe molarity of the permanganate solution is 0.01301 M.The volume of the permanganate solution used is 56.15 mL, which is 0.05615 L.The number of moles of permanganate used is:0.01301 M × 0.05615 L = 0.000730 molThe number of moles of Fe2+ in the sample is:0.000730 mol × 5 = 0.00365 molThe mass of Fe2+ in the sample is:0.00365 mol × 55.845 g/mol = 0.203 gThe mass of the sample is:0.203 g / 0.558 = 0.364 gTherefore, the sample weighs 0.364 g, if it was in fact pure melanterite.

Fe2+(aq)reacts with MnO4-(aq)ion in Acidic Solution to Yield Fe3+(aq)ions and Mn2+(aq)ions

Fe²⁺(aq)reacts with MnO₄^-(aq)ion in Acidic Solution to Yield Fe³⁺(aq)ions and Mn²⁺(aq)ions