Autocatalysis: Reaction of Permanganate with Oxalic Acid
A dilute purple solution of potassium permanganate is added to each of two beakers of acidified oxalate solution. A few crystals of manganese(II) sulfate added to the solution on the right catalyze the reduction of permanganate to colorless manganese(II) ion. Note the initial red color due to formation of a manganese(III) intermediate in the beaker on the right.
The other solution reacts more slowly, but its reaction rate eventually increases as it forms manganese(II) ion, which subsequently autocatalyzes its own formation.
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