[limonade]

.1413g of iron (III) oxalate complex was weighed, transfered to a 125mL erlenmyer flask,, and ~ 30mL of DI water and ~ 5mL of sulfuric acid was added. The solid was dissolved and the flask was heated in a hot water bath to exactly 60 degrees Celsius. The solution was them titrated with .0100M  KMnO4 solution.  The titration did not go to completion until ~70mL of the KMnO4 solution was added. The normal amount of KMnO4 needed to reach the endpoint  should have been ~20.00 to 25.00 mL

What could have possibly gone wrong, chemically, with this reaction?

Notes: burette was read at eye level, no bubbles were present in burette, burette was prerinsed with KMnO4 prior to titration. 

Thanks in advance to any insight

[Borek]

This is rather strange, as I would expect just below 40 mL of the titrant. Apparently it is a matter of guessing what is the reaction taking place.

Presence of iron and oxalic acid makes me think of two possible reactions.