[werdjauregui]

I have to do a titration of oxalic acid with KMnO4, after i get the pilot reading from colorless to light pink do i throw the contents from the flask and add 10ML heat it again or pipette 10ml in the same flask and heat that?

[Borek]

If there is already pink visible, how are going to know what excess of the permanganate was added?

[aga]

Titration is an exact procedure.

The exact quantities of everything must be known for the procedure to give useful information.

Re-using a dirty reaction vessel immediately throws random quanties of random species into the equation, making the results useless.

Always use a clean vessel for any titration procedure.