MnO2 on ignition converts into Mn3O4. A sample of pyrolusite having 75% MnO2,20%inert impurities and rest water is ignited in air to constant weight. What is the percentage of Mn in the ignited sample

sivaji

apply POAC Mn atom

let there be 100g mixture

then wtg. of Mn= 75g now, inert impurities =20g  and xg Mn3O4 is formed

                                   MnO2 = Mn3O4

               for Mn atom  75/87  =3x/229                                                     ( M.W. of MnO2 = 87, M.W. of Mn3O4 =229)

then x=65.8

wt of mn in product = (75/87) * 55=47.41g

%tage of Mn in product = 47.41/(65.8+20)  * 100=55.26% 

Approved