The vapour density of a mixture of NO2 and N2O4 is 38.3 at 26.7oC. Calculate the number of moles of NO2 in 100 g of the mixture.
Suppose NO2 present in 100 g of the mixture = x g
Then N2O4 present in the mixture = (100 – x)g
Molar mass of NO2 = 14 + 32 = 46 g mol–1
Molar mass of N2O4 = 92 g mol–1
Molar mass of mixture
Expressing all quantities in terms of moles, we should have
or 92 x + 4600 – 46x = 5524.8
or 46x = 924.8
or x = 20.1 g
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