Titration of Oxalate by Potassium Permanganate When students start to standardize KMn04 solutions with sodium oxalate, the first titrations often fait because they go too fast and obtain the well-known brownish suspension of Mn02- The oxidation of oxalate is slow at the beginning but becomes faster once the reaction has started. This is due to the catalytic action of the Mn(II) ions formed by the reduction of permanganate.1 Adding a small amount of Mn(II) (±0.02 M final concentration) before starting the titration does not at all alter the ultimate result but limits the failures almost to zero. In so far as we know, no laboratory textbooks for inorganic analysis propose this modification. We have applied it for several years with excellent success. 1
Cullis, C. F., and Ladbury, J. W„ J. Chem. Soc., 555-560 (1955).
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Journal of Chemical Education
