If we represent the reduction of permanganate to manganate,
manganese dioxide and manganese(II) salt by half-reactions,
MnO4
– + e– ® MnO4
2–
(E
o = + 0 56 V)
MnO4
– + 4H+ + 3e– ® MnO2 + 2H2O
(E
o = + 1 69 V)
MnO4
– + 8H+ + 5e– ® Mn2+ + 4H2O
(E
o = + 1 52 V)
We can very well see that the hydrogen ion concentration of the
solution plays an important part in influencing the reaction