The formula mass of Mohr's salt is 392. The iron present in it is oxidised by `KMnO_(4)` in acid medium. The equivalent mass of Mohr's salt is

Options

A. 392
B. `31.6`
C. 278
D. 156

Answer

A

Explanation

Mohr's salt is `(NH_(4))_(2)SO_(4). FeSO_(4).6H_(2)O`.
Oxidation of ferrous salts
`5Fe^(2+)+MnO_(4)^(-)8H^(+)to 5F^(3+)+Mn^(2+)+4H_(2)O`
Total change in oxidation number of Fe
`= (+3)-(+2)=+1`.
`therefore` Equivalent weight of Mohr's salt
`= ("molecular wt. of Mohr's salt")/(1)=(392)/(1)=392`.