Eduard-Job-Foundation for Thermo- and Matterdynamics

Experiment 16.11: Concentration Dependency of Rate of Conversion

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Procedure:
Acidified oxalic acid solution is mixed with differently diluted solutions of potassium permanganate.  

Observation:
The decolorizing process appears first in the most concentrated solution. 

Explanation:
Purple permanganate ions are reduced in acidic solution by oxalate ions to the nearly colorless manganese(II) ions, whereas the oxalate ions are oxidized to gaseous carbon dioxide:

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The higher the dilution, meaning the lower the concentration of the reactants, the more slowly the reaction proceeds. 

Video (mpg4, 3:41)