1.

Grams of a sample of ferrussulphate wasdissolvedin dilutesulphuricacidand waterand itsvolumewas madeup to1 litre .25 mL of this solution required20 mLof N/10KmnO_(4)solutionfor completeoxidation. Calculate thepercentage of FeSO_(4). 7H_(2)Oin the sample .

Answer»

Solution :m.e of `KMnO_(4)"solution "= 1/10 xx 20 = 2 `
` :. ` m.eof 25 mLof `FeSO_(4) . 7H_(2)O " solution "= 2 "" …. (Eqn . 1)`
` :. ` m.eof 100m Lof `FeSO_(4). 7H_(2)O"solution " = 2/25 xx 1000 = 80`
Equivalent of `FeSO_(4) . 7H_(2)O = 80/1000 = 80 `
Equivalent of `FeSO_(4) . 7H_(2)O`solution = `2/25 xx 1000 = 80`
Equivalent of `FeSO_(4) . 7H_(2)O = 80/1000 ""...(Eqn . 3)`
` :. ` weightof `FeSO_(4) .7H_(2)O` = equivalent `xx` eq.WT
` = 80/100 xx278 = 22.4 G `
`{ "As " FE^(2+)to Fe^(3) ," eq . wt of " FeSO_(4) . 7H_(2)O= (mol . w.t )/(" changein ON ") = 278 / 1 } `
thusthe percentage of `FeSO_(4). 7H_(2)O ` in the sample` = (22.24)/25 xx 100`
` = 88.96 %`


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