In permanganate titrations, potassium pemanganats is used an an oxidizing agent in acidic medium. The medium is maintained acidic by the use of dilute sulphuric acid. Potassium permanganate acts as self indicator . The potential equation, when potassium permanganate acts as an oxidizing agent is 2KMnO_(4) + 3H_(2)SO_(4) to K_(2)SO_(4) + 2MnSO_(4) + 3H_(2)O + 5[O] or MnO_(4)^(-) + 8H^(+) + 5e^(-) to Mn^(2+) + 4H_(2)O Before the end point, the solution remains colourless but after teh equivalence point only one extra drop of KMnO_(4) solution imparts pink colour , i.e. appearance of pink colour indicates end point. These titrations are used for estimation of ferrous salts, oxalic acid, oxalates, hydrogen peroxide, As_(2)O_(3) etc. Mass of KHC_(2)O_(4) (potassium acid oxalate ) required to reduce 100 ml of 0.02 KMnO_(4) in acidic medium (MnO_(4)^(-)" changes to " Mn^(2+)) is x gm and to neutralize 100 ml of 0.05M Ca(OH)_(2) is y gm ,then