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Microchem
Microscale Chemistry Experimentation for Teachers
 
 

Redox titration of Fe(II) sulfate by acidic solution of potassium permanganate

Left: 1.0 ml of a very diluted solution of KMnO4 is sucked into a 1-ml syringe (microscale measuring burette).
A second 1-ml syringe (microscale measuring pipette) is filled with exactly 1.0 ml of a very diluted (test solution) of FeSO4.
A magnifier lense is used to read the volume.
Photo 2: In a 5-ml vial 1 ml of the of FeSO4 solution is mixed with 1 drop of H2SO4 conc.
Photo 3: Microdrops of KMnO4 are added to the vial which is shaked after each addition of the pink solution which decolourizes. The end point of the titration corresponds to the faintest purple colour in the solution.
When all the Fe2+-ions are consumed the purple colour of the MnO4- ions persist.
Right: A volume of 40 units of KMnO4 solution is still in the syringe which means that 0.6 ml of measuring solution were consumed for the oxidation of Fe2+:

5 Fe2+(aq) +  8 H+(aq) + MnO4-(aq) ---------redox----> 5 Fe3+(aq) +  8 H2O + Mn2+(aq)
Copyright: M.K.El-Marsafy            first published: 07.11.2000     last modification: 24.05. 2001              back