1.6 g of pyrolusite ore was treted with 50 " mL of " 1.0 N oxalic acid and some sulphuric acid. The oxalic acid left undecomposed was raised to 250 mL in a flask. 25 " mL of " this solution, when titrated with 0.1 N `KMnO_4` required 32 " mL of " this solution. Find out the percentage of pure `MnO_2` and also the percentage of available oxygen from `MnO_2`.

Explanation

Meq.of `MnO_(2)=` Meq.of oxalic acid added-Meq.of oxalic acid left
`=1xx50-0.1xx32xx10=18 ("in" 250 mL)`
`( :. E=(86.9)/(2))`
or `:. (w)/(E )xx1000=18`
or `w_(MnO_(2))=(18xx86.9)/(2xx1000)=0.7821g`
`:. % "of" MnO_(2)=(0.7821)/(1.6)xx100=48.88%`
Also Meq.of `MnO_(2)="Meq.of" O_(2)=18`
`:. (w)/(8)xx1000=18`
`w_(O_(2))=0.144g`
`:. %` of available `O_(2)=(0.144)/(1.6)xx100=9%`