In the oxidation of oxalate ion, #C_2O_4^(2-)# to give carbon dioxide by potassium permanganate, #K^(+)MnO_4^(-)#, how do we vizualize the endpoint?
Disappearance of the deep purple/violet colour.
Permanganate ion, which gives intense purple solutions, is reduced to
The first drop of permanganate titrant delivered after the end point, delivers a very noticable purple colour. And thus the endpoint can be easily perceived.
Oxalate ion is oxidized up to carbon dioxide:
So to balance the redox equations, we cross mulitply to remove the electrons:
Very concentrated solutions of