How is #"Mohr's salt"# oxidized by #"potassium permanganate"# to give #Fe^(3+)# and #Mn^(2+)#? How is #"hydrogen peroxide"# oxidized by the same reagent to give #"dioxygen gas"#?
Well, in the first scenario,
You used the so-called
Note that the ammonium ions, and the sulfate ions are simply along for the ride. They do not take place in the redox transition, and so may be eliminated from consideration. Meanwhile the electron acceptor, was the OXIDANT, the permanganate ion. This is reduced from
And what we would we observe in the reaction? The macroscopic colour change observed would be from deeply purple (the permanganate colour) to almost colourless
And in the second scenario,
And again we cross-multiply:
Which (I think) is balanced with respect to mass and charge.
Again, you can very accurately determine the stoichiometric endpoints by means of the pronounced colour change.
If I have missed the point of your question, would you clarify?