[LHM]

A solution of which substance can best be used as both a titrant and its own indicator in an oxidation-reduction titration?

A) I₂
B) NaOCl
C) K₂Cr₂O₇
D) KMnO₄

The answer is the potassium permanganate, but why is this the answer?

Thanks.

[opti384]

Both b and c are commonly used in oxidation-reduction titration, but since potassium permanganate can be

reduced in different forms depending on whether the solution is acidic, neutral or base the answer will be c.

[Borek]

Both b and c are commonly used in oxidation-reduction titration, but since potassium permanganate can be

reduced in different forms depending on whether the solution is acidic, neutral or base the answer will be c.

No, that's not the correct answer. Dichromate color is not intense enough.

[LHM]

Both b and c are commonly used in oxidation-reduction titration, but since potassium permanganate can be

reduced in different forms depending on whether the solution is acidic, neutral or base the answer will be c.

No, that's not the correct answer. Dichromate color is not intense enough.

Just double-checking, are you saying then that the answer is D because its colors are the most intense, and it doesn't have anything to do with being reduced to different forms?

[opti384]

Oops. I meant that the answer is D. I have mistakenly wrote that the answer is C.

[Borek]

Just double-checking, are you saying then that the answer is D because its colors are the most intense, and it doesn't have anything to do with being reduced to different forms?

You have full control over the final form, as long as you select correct pH for the reaction. In a titration we usually go for low pH and Mn²⁺.