The concentration of a solution of potassium permanganate is determined by titrating it into an Erle — Laboratory Chemistry Question
Question
The concentration of a solution of potassium permanganate is determined by titrating it into an Erlenmeyer flask with solid ferrous ammonium sulfate hexahydrate (Fe(NH4)2(SO4)2 • 6 H2O) dissolved in dilute sulfuric acid. Which error would result in a measured concentration of KMnO4 that is lower than the actual concentration?
A.
The titration was begun before the ferrous ammonium sulfate had fully dissolved in the sulfuric acid.
B.
The sides of the Erlenmeyer flask were periodically rinsed down with deionized water during the titration.
C.
Some of the Fe(II) ions in the solid ferrous ammonium sulfate had been oxidized to Fe(III) on storage.
D.✓ Correct
The buret was rinsed with distilled water and then filled with KMnO4 solution while still wet.
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