Titration of Oxalate by Potassium Permanganate When students start t o standardize KMnOl solutions with sodium oxalate, the first titrations often fail because they go too fast and obtain the well-known brownish suspension of MnOz. The oxidation of axalate is slaw a t the beginning but becomes faster once the reaction has started. This is due to the catalytic action of the Mn(lI) ions formed by the reduction of permanganate.' Adding a small amount of Mn(1I) (*0.02 M final concentration) before starting the titration does not a t 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.
'Cullis, C. F., and Ladbury, J. W., J. Chem. Soe., 555-560 (1955). Jef Helsen Universiteit te Leuven de Croylaan, 2 3030 Heverlee, Belgium
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