1.

A sample of Fe(SO_4)_3 and FeC_2O_4 was dissolved in H_2SO_4. 40 " mL of " (N)/(16)KMnO_4 was required for complete oxidation. After oxidation the mixture was reduced by (An)/(H_2SO_4). On again oxidation by same KMnO_4, 60 mL was required. Calculate the ratio of m" Eq of "Fe_2(SO_4)_3 and FeC_2O_4.

Answer»

Solution :`FeC_2O_4+H_2SO_4toFeSO_4+(COOH)_2`
`Fe^(2+)toFe^(3+)+e^(-)`
`C_2O_4^(2-)to2CO_2+2e^(-)`
40 " mL of " `(N)/(16)` `KMnO_4=(40)/(16)` m" Eq of "`(Fe^(+2)+OX^(2-))`
Let us TAKE y m " mol of "`Fe^(2+)`
`THEREFORE m" Eq of "Fe^(+2)=y` (n factor`=1`)
y m " mol of "`OX^(2-)`
`thereforem" Eq of "OX^(2-)=2y` (n factor`=2`)
`thereforey+2y=(40)/(16)implies3y=(40)/(16)becausey=(40)/(48)`
m" Eq of "`Fe^(2+)=(40)/(48)`, `m" Eq of "Fe_2C_2O_4=(40)/(16)`
Second step:
60 " mL of " `(N)/(16)KMnO_4=(60)/(16)` m" Eq of "total `Fe^(2+)` LTBRGT `[Fe^(2+)` ions from `FeC_2O_4+Fe^(2+)` ions obtained after the reduction of `Fe_2(SO_4)_3]`
m" Eq of "`Fe_2(SO_4)_3=(60)/(16)-(48)/(48)=(140)/(48)`
RATIO of MEQ`(Fe_2(SO_4)_3)/(FeC_2O_4)=(140xx48)/(48xx40)=(7)/(6)=7:6`


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