Pyrolusite is the main ore of manganese in which it is present asIts Mn content is determined by reducing it under acidic condition to Mn^(2+)with the help of oxalate (C_(2)O_(4)^(2-)) ion which in turn gets oxidized to CO_(2) The analytical determination is carried out by adding a known excess volume of (C_(2)O_(4)^(2-)) solution to a suspension of the pyrolusite and digesting the mixture on a hot water bath until all the MnO_(2) has been reduced. The excess unreacted oxalate solution is then titrated with standardized KMnO_(4) solution. Thereby Mn content of ore can be calculated. KMnO_(4)solution is also standardized under acidic condition against oxalate ion wherein MnO_(4)^(-) ion is reduced to Mn^(2+) and (C_(2)O_(4)^(2-)) ion is oxidized to CO_(2)Q An alternative method for this analysis may be the replacement of oxalate with Fe^(2+) But this is less frequently used because it requires some special care otherwise we get low analytical results. The probable reaction responsible for this fact is :

Pyrolusite is the main ore of manganese in which it is present asIts M

1.	Pyrolusite is the main ore of manganese in which it is present asIts Mn content is determined by reducing it under acidic condition to Mn^(2+)with the help of oxalate (C_(2)O_(4)^(2-)) ion which in turn gets oxidized to CO_(2) The analytical determination is carried out by adding a known excess volume of (C_(2)O_(4)^(2-)) solution to a suspension of the pyrolusite and digesting the mixture on a hot water bath until all the MnO_(2) has been reduced. The excess unreacted oxalate solution is then titrated with standardized KMnO_(4) solution. Thereby Mn content of ore can be calculated. KMnO_(4)solution is also standardized under acidic condition against oxalate ion wherein MnO_(4)^(-) ion is reduced to Mn^(2+) and (C_(2)O_(4)^(2-)) ion is oxidized to CO_(2)Q An alternative method for this analysis may be the replacement of oxalate with Fe^(2+) But this is less frequently used because it requires some special care otherwise we get low analytical results. The probable reaction responsible for this fact is :
Answer» presence of oxygen can cause OXIDATION, `Fe^(2+)toFe^(3+)` presence of oxygen can cause reduction, `Fe^(3+)toFe^(2+)` the oxidation of `Fe^(2+)toFe^(3+)` is difficult in the presence of `C_(2)O_(4)^(2-)` formation of `CO_(2)` reduces `Fe^(3+)toFe^(2+)` Solution :Due to the pressure OFOXYGEN, `Fe^(2+)`READILY gets oxidised to `Fe^(2+)`