1.

A 1.00- g sample of H_(2)O_(2)solution containing x percent H_(2)O_(2)by weightrequiresx mLof a KMnO_(4)solution for complete oxidation under acidic conditions .Calculate the normality of the KMnO_(4) solution .

Answer»

Solution :`{:(2MnO_(4),+ 5H_(2)O_(2),6H^(+),to 5O_(2),+ 2Mn^(2+),+8H_(2)O),((+7),,,,(+2),):}`
FROMTHE equation , we see that
change in oxidation number of Mn = `7-2 = 5`
` :. ` 1 MOLE of `KMnO_(4)` = 5 EQ. og `KMnO_(4)`
` :. ` 10 eq. of ` KMnO_(4)`= 5 eq. of `KMnO_(4)`
` :. ` 10 eqof `KMnO_(4)`combines with 5 moles of `H_(2)O_(2)` .
` :. ` 1 eq . of `KMnO_(4)` combines with `1/2 ` mole of `H_(2)O_(2)`
` :. ` eq.wt of `H_(2)O_(2)= 34/2 = 17`
Now ,
` :.100 ` g of `H_(2)O_(2)`solution contains X g of `H_(2)O_(2)`
` :. 100` g of `H_(2)O_(2)`contains `x/17`equivalent of `H_(2)O_(2)`
` :. 1 ` g of `H_(2)O_(2)` contains `x/(17 xx100) ` eq. of `H_(2)O_(2)`
` :. ` number of m.e of `H_(2)O_(2)` in 1 g solution = `x/(17 xx100) xx 1000`
` = (10 x)/17`
m.e of `H_(2)O_(2)` = m.eof `KMnO_(4)`
`(10 x)/17 = x N `
( N = normality of `KMnO_(4)`)
`:. ` normality of `KMnO_(4)` solution = `10/17eq. " lit"^(-1)`


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