Question

The vapour density of a mixture of NO2 and N2O4 is 38.3 at 26.7 oC. Calculate the number of
moles of NO2 in 100 g of the mixture.

Answer 1

Answer:

Let the total number of moles = 1

let the number of moles of NO2 = X

so number of moles of N2O4 = 1 -x

molar mass of mixture = 2 x vapour density

= 2 × 38.3 = 76.6

Now x × 46 + ( 1-x) 92 = 76.6

46 x + 92 -92 X = 76.6

46 x = 15.4

x = 15.4 / 46 = 0.335

% age of NO2 = 33.5 %

% age of N2O4 = 66.5 %

Number of moles NO2 in 100 g of mixture =0.335 × 100 / 76.6 = 0.437

Explanation: