[peterschmidt3943]

Hello,

reaction: MnO4- + 5e- + 8H+    Mn2+ + 4H2O

In which milieu (pH value) can the reaction only take place and why?

I would say a pH < 7 because of the protons ?

[Borek]

Pourbaix diagram should help.

[peterschmidt3943]

How do I create it ? Ive never done nor heard of of it..

[Borek]

Google - you don't have to create it, just use one prepared by others.

[peterschmidt3943]

is there also another way of finding out simply in which pH range it reacts?

[peterschmidt3943]

I thought of using the Nernst equation:

E= 1,51 + (0,06)/5 * lg[Ox]/[Reduction agent]

1,51 equals E° (I looked it up)

which values do I have to substitute for [Ox] and [Reduction agent] ? They are not given...

[Borek]

I am not convinced the question - as stated - can be easily answered. Way too many factors involved. A lot will depend on the presence of other substances in the solution and on the reducing agent.

In general if the MnO₂ is more stable than Mn²⁺ reaction will end at the oxide state.