1.

On passing 10.0 L of a gaseous mixture of NO_(2) and N_(2) at STP, through an NaOH solution, a mixture of NaNO_(2) and NaNO_(3) is formed 6.32 g of KMnO_(4) is required to oxidise above NaNO_(2) in H_(2)SO_(4) medium. Determine the percentage by mass of gaseous mixture (N_2 does not react with NaOH)

Answer»

Solution :`2NO_(2)+2NaOHtoNaNO_(3)+NaNO_(3)+NaNO_(2)+H_(2)O`
" EQ of "`KMnO_(4)=" Eq of "NO_(2)^(ɵ)`
`{NO_(2)^(ɵ)toNO_(3)^(ɵ)(x=2)]`
" Eq of "`KMnO_(4)=(6.32)/(31.5)=Eq. of NO_(2)^(ɵ)`
Moles of `NO_(2)^(ɵ)=(6.32)/(31.5)xx(1)/(2)=0.1 MOL`
Weight of `NO_(2)^(ɵ)=0.1xx69=6.9g`
Weight of `NaNO_(2)=6.9g`
From the above equation
`0.1 " mol of "NaNO_(2)-=0.2 mol NO_(2)`
`-=0.2xx22.4L at STP`
`-=4.48 L NO_(2)`
Volume of `N_(2)=(10-4.48)=5.52L`
`=0.246L N_(2)`
Mole of `NO_(2)=0.2=0.2xx46=9.2g`
Mole of `N_(2)=0.246=0.246xx28=6.89g`
`% of NO_(2)=57.18,% of N_(2)=42.82g`


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