A mixture of `NO_(2)` and `N_(2)O_(4)` has a vapor density of `38.3` at 300 K. What is the number of moles of `NO_(2)` in 100 g of themixture ?

Options

A. `0.043`
B. `4.4`
C. `3.4`
D. `3.68`

Explanation

Average mol. Mass of mixture `= 2xxV.D.`
`=2xx38.3=76.6`
Let mixture contains a moles of `NO_(2)` and b moles of `N_(2)O_(4)`
`:.(axx46+bxx92)/(a+b)=76.6`
(Molar mass of `NO_(2) = 46g mol^(-1)`, molar mass of `N_(2)O_(4) = 92g mol^(-1)`
Let mass of `NO_(2)` = x and mass of `N_(2)O_(4) = 100-x`
`:. a=(x)/(46)` and `b=(100-x)/(92)`
`:. (x+100-x)/((x)/(46)+(100-x)/(92)) = 76.6`
`(x)/(46)+(100-x)/(92)=(100)/(76.6)`
`x = (100xx15.4)/(76.6)`
No. of moles of `NO_(2), a = (x)/(46)`
`=(100xx15.4)/(46xx76.6)=0.437`