the vapour density of a mixture containing NO2 and N2O4 is 38.3 at 27 degree celsius. calculate the mole of NO2 in 100 molemixture.
Let us assume that there are x moles of NO2 in the mixture. Hence, there will be (100-x) moles of N2O4 in the mixture (since total number of moles is 100).
We know that 1 mole of NO2 weighs 46g (14 + 2*16) and
1 mole of N2O4 weighs 92g (2*14 + 4*16)
Total molecular mass of the mixture = x*46 + (100-x)92
We also know that Molecular mass = 2 * Vapour density
= 2 * 38.3
Molar mass of mixture = Mass of mixture / (Number of moles of NO2 + Number of moles of N2O4)
Molar mass of mixture = Mass of mixture / (x + 100 –x)
Therefore, (46x + (100-x)92)/100 = 76.6
46x + 9200 – 92x = 7660
46x = 1540
Therefore, x = 33.48 moles. i.e., 33.48 moles of NO2 are present in the mixture.