Why is potassium permanganate(VII) such a strong oxidising agent, why does its behaviour depend on pH of the solution it is present in?

Why is potassium permanganate such a strong oxidizing agent? Let is say we have a $\ce{KMnO4}$ aqueous solution which is acidified by adding sulfuric acid. What is going on in the solution which makes it so oxidizing that immediately if we add an organic or inorganic molecule it gets immediately oxidized?


Also why under different pH potassium permanganate behaves differently i.e. Mn reduces from +7 to +2 in acidic conditions whereas it goes to +4 in neutral conditions?


