Question

Why k2cr2o7 is not self indicator in mohrs salt titration?

Answer 1

Potassium dichromate acts as oxidizing agent in acidic medium only. it can't be used as a self indicator like KMnO4. this is because its reduction product (Cr3+) is green which hinders in the visual detection of end point by observing dichromate colour. Thus an indicator is must in this titration.