In the given reaction determine the equivalent weight of of `As_(2)S_(3)`: [Assume that M.W of `As_(2)S_(3)=M`]
`As_(2)S_(3)+7CIO_(3)^(-)7OH^(-)to2AsO_(4)^(3-)+7CIO^(-)+3SO_(4)^(2-)+6H_(2)O`

Explanation

In the given reactions ,both S and As -atoms of the `As_(2)S_(3)` molecule are oxidised
`overset(+3-2)(As_(2)S_(3))tooverset(+5)AsO_(4)^(3-)+overset(+6)SO_(4)^(2-)`
The increases in oxidation number of each As-atoms =5-3=2 unit .SO, the total increase in oxidation number of two As-atoms =`2xx2=`4 unit.
The increases in oxidation number of each s- atom =+6-(-2)=8. Therefore ,the total increase in oxidation number of three S- atoms =3xx8=24unit.
Hence the total increases in oxidation number for each `As_(2)S_(3)`molecule in its oxidation in its oxidation is =(24)+4=28 unit.
`therefore`Equivalent weight of `As_(2)S_(3)` in the given reaction
`("Molecular weight of" As_(2)S_(3))/("Increase in oxidation number")=(M)/(28)`