Chemistry · Analytical Chemistry

Potassium permanganate (KMnO₄) is used as its own indicator because it changes color distinctly at the endpoint of a titration in an acidic medium. The intense purple color of KMnO₄ fades to colorless (or a very faint pink) as it is reduced, providing a clear visual cue without the need for an additional indicator. In contrast, K₂Cr₂O₇, Iodine, and H₂O₂ lack such a distinct color change when used in acidic conditions, making them unsuitable as self-indicators.

K₂Cr₂O₇ is a powerful oxidizing agent but does not serve as its own indicator in acid medium since it does not show a distinct color change upon reaction completion.

Iodine does not serve as its own indicator in acid medium as it lacks a distinct color change at the endpoint and is typically used with starch as an indicator in iodometric titrations.

KMnO₄ is a strong oxidizing agent that acts as its own indicator due to its distinct color change from purple to colorless or light pink in acid medium at the endpoint of the titration.

H₂O₂ does not exhibit a visible color change in acid medium and is not used as its own indicator in titrations.