The corresponding equation for acidic solutions can be obtained by adding enough hydrogen ions to each side to eliminate the hydroxide ions:





Example.
Potassium permanganate, , is a common inorganic oxidizing agent, which becomes reduced to manganous ion, Mn, in acidic solution. Write a balanced equation for the reaction in which permanganate oxidizes ferrous iron, Fe²⁺, to ferric ion, Fe³⁺.

Solution.


In the permanganate ion manganese has an oxidation number of +7 which decreases to +2 in the manganous ion, a change of -5. Iron increases in oxidation number by one: