Question

To measure the quantity of `MnCl_(2)` dissolved in an aqueous solution, it was completely converted to `KMnO_(4)` using the reaction.

Answer 1

Correct Answer - 126 mg
The chemical equation involved in the conversion of `MnCl_(2) " to " KMnO_(4)` is :
`MnCl_(2) +K_(2)S_(2)O_(8)+H_(2)O to KMnO_(4)+H_(2)SO_(4)+HCl`
Balanced ionic equation will be :
`2Mn^(2+)+5S_(2)O_(8)^(2-)+8H_(2)O to 2MnO_(4)^(2-) +10SO_(4)^(2-)+16H^(+)`
Ionic equation involved in the oxidation of oxalic acid by `KMnO_(4)` in acid medium is :
`2MnO_(4)^(-)+6H^(+)+5{:(COO^(-),),(|,),(COO^(-),):}to2Mn^(2+)+8H_(2)O+10CO_(2)`
Number of moles of `MnCl_(2)=("Number of moles of oxalic acid")/(2.5)`
`=(0.225//90)/(2.5)=1xx10^(-3)`
Mass of `MnCl_(2)=0.001xx126g`
=0.126 g =126 mg