write balanced chemical equations for action of potassium permanganate on :
(a) Hydrogen
(b) Warm conc. Sulphuric acid
Explain why `Mn^(2+)` ion is more stable than `Mn^(3+)` ?
(given : `MntoZ=25` )

Explanation

(a) When potassium permanganate `KMnO_(4)`, is heated in a current of `H_(2)` , KOH, MnO and steam are formed.
`2KMnO_(4)+5H_(2)to2KOH+underset("oxide")underset("Managanese")(2MnO)+4H_(2)O`.
(b) When `KMnO_(4)` is heated with warm concentrated `H_(2)SO_(4),K_(2)SO_(4),MnSO_(4)` and five O-atoms rendered available from `MnO_(4)^(-)` ions are formed.
`2KMnO_(4)+underset(("Warm conc."))(3H_(2)SO_(4))toK_(2)SO_(4)+2MnSO_(4)+3H_(2)+5O`
`Mn^(2+)` more stable than `Mn^(3+)` :
The electronic configuration of `Mn_(25)` is `[Ar]_(18)4s^(2)`
`3d^(5),Mn_(23)^(2+)` is `[Ar]_(18)4s^(0)3d^(5)andMn_(22)^(3+)to[Ar]_(18)4s^(0)`
`3d^(4)`. We know, half filled or full electronic configuration is more stable than partially filled electronic configuration. `Mn^(2+)` has partially filled electronic configuration. `Mn^(2+)` has half filled d-orbital whereas `Mn^(3+)` has partially filled d-orbital. Hence, `Mn^(2+)` is more stable than `Mn^(3+)`.