# chemistry

posted by
**sumati**
.

The vapour denisty of a mixture containing NO2 & N2O4 is 38.3 at 27 deg C. Calculate the moles of NO2 in 100 g of mixture.

The vapor density is the mass of a volume of the mixture divided by the mass of an equal volume of H2 at the same P and T. If we take a mole sample, then

(molar mass mixture/2.016) = 38.3

molar mass mixture = 2.016*38.3= ??

Then let f = fraction of NO2 in the mixture and 1-f = fraction of N2O4.

molar mass NO2 = 46

molar mass N2O4 = 92

46(f) + 92(1-f) = 2.016*38.3

Solve for f.

then f x 100 = grams NO2.